TCG Price Tracker: Build Your Own Alerts for Booster Boxes and ETBs

Stop Missing Real TCG Deals: Build a Price Tracker That Alerts You When Booster Boxes and ETBs Hit True Bargains

Hate chasing expired coupon codes and wondering if that “Amazon deal” is actually worth it? You’re not alone. TCG prices swing fast around set releases, omnichannel promos, and flash sales. This guide shows exactly how to build a practical, reliable TCG price tracker—using marketplaces, browser extensions, saved searches, and a simple spreadsheet—to set booster box alerts and ETB discounts that only trigger on true bargains.

What you’ll learn (quick)

• How to watch Amazon, TCGplayer, eBay and Cardmarket for booster box alerts and ETB discounts.
• Which browser extensions and tools (Keepa, CamelCamelCamel, extensions, RSS) actually work in 2026.
• How to log price history in Google Sheets and set automated set alerts and notifications.
• Rules to define a “true deal” (vs noise), and real examples using Edge of Eternities and Phantasmal Flames.

Why smart alerts matter in 2026

Retail and TCG marketplaces changed a lot between 2023–2026. Retailers doubled down on omnichannel experiences and dynamic pricing, making short-lived markdowns common. A study referenced by Digital Commerce 360 and Deloitte showed retailers prioritized omnichannel investments in 2026—so flash price drops, BOPIS promos, and regional discounts are more frequent than before.

“46% of retail execs listed omnichannel experience enhancements as their top 2026 growth priority.” — Deloitte (2026)

That means the deals you see on Amazon or in email blasts can be legitimate wins—or temporary price anomalies. A TCG price tracker gives you objective context: historical price, market comparison, and thresholds that tell you when to buy.

Essential tools for a DIY TCG price tracker

Marketplaces to watch (and why)

• Amazon — fast drops and lightning deals on booster boxes. But sales include Amazon, FBA, and 3P sellers; price history tools are essential.
• TCGplayer — the go-to for card and sealed market pricing. Use its product pages and seller market prices as a benchmark.
• eBay — best for tracking real sold prices (look at Sold Listings), especially for secondary market spikes after hype sets.
• Cardmarket (Europe) — essential if you cross-shop EU listings.
• Retail chains (Walmart, Target, GameStop) — often part of omnichannel promos or exclusive bundles.

Browser extensions and monitoring services

• Keepa (extension & API) — gold standard for Amazon price history and drop alerts. Keepa lets you see long-term price charts and set custom alerts. Note: Keepa API access has fees but is reliable for automated tracking.
• CamelCamelCamel — free Amazon price tracker with email alerts and public charts. Good lightweight option.
• OctoShop — compares marketplace prices and can alert for price falls.
• eBay saved searches & RSS — use saved search alerts or the RSS feed for that search to trigger notifications via IFTTT or Zapier.
• Telegram/Discord bots — many communities run bots that scrape marketplaces and post price drops in channels (great for teeth-gnashing real-time alerts).

Fast setup: three levels depending on your comfort

Level 1 — No-code (recommended if you want fast wins)

1. Create Amazon alerts with Keepa or CamelCamelCamel for specific booster box ASINs and ETB SKUs.
2. Save searches on eBay for the set name + "booster box" or "elite trainer box" and enable email alerts.
3. Use TCGplayer product pages and add to your TCGplayer watchlist where available.
4. Use IFTTT or Zapier to route CamelCamelCamel/rss/email alerts to your phone via SMS, email, or Slack/Discord webhook.

Level 2 — Semi-automated (best balance)

1. Install Keepa extension and set alerts for price thresholds and % drops.
2. Create a Google Sheet with links and manual daily checks for TCGplayer and Cardmarket prices.
3. Use eBay RSS + Zapier to append new sold listing prices into a Google Sheet (Zapier can add rows automatically).
4. Set Google Sheets conditional formatting and an Apps Script to send an email when a new price row meets your threshold.

Level 3 — Full automation (for power users)

• Get keys for Keepa API and TCGplayer API (TCGplayer requires developer sign-up). Optionally use eBay API.
• Use a Google Apps Script (sample snippet below) or a small server (AWS Lambda/Glitch) to poll APIs daily and store results in BigQuery or Google Sheets.
• Compute 7/30/90-day moving averages and set alerts for 15%+ below 90-day avg OR below the lowest market seller price.
• Deliver alerts via SMS (Twilio), Telegram, Discord, or push notifications (Pushover).

Sample Apps Script (fetch a JSON endpoint into Google Sheets)

// PSEUDOCODE: replace URL with Keepa/TCGplayer endpoint
function fetchPriceToSheet(){
  const sheet = SpreadsheetApp.getActive().getSheetByName('Prices');
  const response = UrlFetchApp.fetch('https://api.example.com/price?sku=XYZ&key=API_KEY');
  const data = JSON.parse(response.getContentText());
  sheet.appendRow([new Date(), data.price, data.seller, data.market_avg]);
}
  

Note: Amazon blocks scraping. Use Keepa or CamelCamelCamel for reliable Amazon price history and avoid scraping directly.

How to define “true deal” — rules that keep alerts useful

Set rules that filter out noise and stop false alarms. Use a combination of these rules to trigger a buy alert:

• Historical floor rule: Price <= all-time low OR >= 12% below the 90-day average.
• Market gap rule: Price at retailer is >= 10% below the lowest trusted reseller (TCGplayer / Cardmarket / major seller).
• Absolute threshold rule: Price <= your maximum acceptable price (e.g., $140 for a 30-pack MTG booster box).
• Stock & seller rule: Only alert if in-stock and sold by Amazon or a seller with 95%+ rating or a top TCGplayer seller.
• Bundle check: Ensure the listing is not a used box, missing items, or includes nonstandard packaging that reduces value for collectors.

Interpreting historical pricing: what to chart and why

When tracking price history for MTG or Pokémon, collect daily rows of:

• Date
• Retail price (Amazon / retailer price)
• Market floor (lowest TCGplayer or Cardmarket sealed price)
• eBay sold price average (last 30 days)
• Stock level / seller count (if possible)

From there compute:

• 7/30/90-day moving averages to identify trends and noise.
• Percent delta between retail and market floor (helps decide if box or singles resale is profitable).
• Volatility index—standard deviation of price over 30 days to flag unstable releases.

Real examples: Amazon MTG deals and ETB discounts (how a tracker would catch them)

Example 1 — Edge of Eternities booster box on Amazon

On a recent Amazon sale the Edge of Eternities booster box dropped to $139.99. Your tracker should answer:

• Is $139.99 below the 90-day avg? (If the 90-day avg is $164.70, this is ~15% off.)
• Is it below the market floor? (Compare to TCGplayer/other resellers.)
• Is shipping/tax or a marketplace seller fee pushing effective cost above your buy threshold?

If your rules are “>= 12% below 90-day avg OR >= 10% below market floor,” this would trigger a buy alert because it meets both.

Example 2 — Phantasmal Flames ETB below market price

Amazon listed Phantasmal Flames ETB at $74.99—below trusted reseller price of $78.53 on TCGplayer. Your tracker should:

• Catch that retail price is below the market floor and under your absolute threshold (e.g., $80 for ETB).
• Verify stock and whether the box is sealed and seller-rated.
• Notify you via mobile or Slack immediately; ETB stock can evaporate fast.

Quick math: decide instantly if a deal is worth buying

Use this quick worksheet in your head (or in a spreadsheet):

1. Retail Price: $R
2. Market Floor: $M
3. Shipping & Fees: $F
4. Effective Cost = R + F
5. Delta = (M - Effective Cost) / M

If Delta >= 0.10 (10%), that’s typically a solid margin for resale or a clear collector saving. For pure play/collectors prioritize lower risk (seller reputation, returns allowed).

Advanced: build a comparative price comparison tool inside Google Sheets

Why build one? So you can see Amazon vs TCGplayer vs eBay vs Cardmarket in one view and set a combined alert like “Retail <= weighted market average - 12%.”

1. Use Keepa API to pull Amazon price history.
2. Pull TCGplayer prices via their API or manually scrape product pages into the sheet (respectful rate limits).
3. Use eBay saved search/sold listings RSS and Zapier to append sold prices to the sheet.
4. Compute a weighted market price: 50% TCGplayer market, 30% eBay sold avg, 20% Cardmarket (or adjust by region).
5. Trigger an Apps Script email when Retail <= weighted_market * 0.88 (12% below).

Trust & verification: avoid the pitfalls

• Always verify seller rating and return policy for third-party Amazon listings.
• Watch for listings that are marked “new” but are repacked — especially with ETBs and collector boxes.
• Check shipping timelines—some “cheap” offers lock you into long lead times or restock waitlists.
• When in doubt, prefer FBA or major TCG retailers—fast confirmation + returns reduces risk.

Seasonality and set lifecycle: why price history matters for MTG & Pokémon

Prices follow a predictable path for many sets:

• Launch period: spikes for hyped sets or short supplies.
• Post-launch decline: retail oversupply and promos push prices down.
• Rotation/Format changes: MTG Standard rotations heavily influence sealed pricing.
• Long-tail collector interest: unique chase cards or reprints can revive demand.

Tracking price history across these phases helps you know when a sale is a short-term dip or a real buy window.

Templates & checklist (practical takeaways)

Quick setup checklist

• Install Keepa and set alerts for target ASINs.
• Create eBay saved searches & subscribe to RSS alerts.
• Make a Google Sheet labeled: Date, SKU, Retail, Market Floor, eBay Avg, Notes.
• Decide your rule (e.g., >=12% below 90-day avg OR >=10% below market floor).
• Route alerts to phone via Zapier/IFTTT or use Apps Script to email when rules are met.

Buy-or-wait rule of thumb

• Buy: Price <= 12% below 90-day avg AND seller trust high.
• Wait: Price is 5–10% below avg but market volatility is high (SD large).
• Ignore: Price drop with low seller rating, used condition, or long shipping delay.

Final notes: staying ahead in 2026 and beyond

2026 brought smarter retail tooling—better omnichannel offers, more AI-driven personalized discounts, and faster flash sales. That makes DIY tracking both more necessary and more powerful. Use a layered approach:

• Quick wins with Keepa/CamelCamelCamel and eBay saved searches.
• Medium-effort automation with Google Sheets + Zapier for historical tracking.
• Full automation with APIs if you track many SKUs daily.

Keep your rules conservative at first: you’ll get fewer false positives and higher confidence when the alert truly means “buy now.”

Ready to set up your first TCG price tracker?

Start small: pick one booster box and one ETB you’d actually buy. Install Keepa and set a 12% below 90-day average alert. Create a simple Google Sheet row for daily price, and add an eBay saved search. Test this for two weeks and tune thresholds based on how often alerts are useful.

Want a free starter template? We put together a plug-and-play Google Sheet and a checklist tailored for MTG and Pokémon (booster box & ETB) workflows—complete with suggested alert thresholds and sample Apps Script snippets. Get it, customize it, and never miss a true deal again.

Take action now: set up your first alert and add the two SKUs you care about. The next real ETB discount or Amazon MTG deal could be hours away—don’t let fresh stock pass by because you didn’t have a tracker.

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