About & Methodology
How we calculate fair value, what our data sources are, and how to use our API.
What is Card Comp Search?
Card Comp Search aggregates real-time eBay data to help collectors and sellers understand fair market value for sports cards and TCG cards. We surface recently sold "comps" (comparable sales), active Buy It Now listings, and upcoming auction endings all in one place — so you can make informed decisions without digging through eBay manually.
How Fair Value is Calculated
Our suggested price is derived from the 25th percentile (P25) of recent sold listings for a given search query. Here's why:
- P25 is the lower quarter of recent sales. It filters out outlier high-end sales while still reflecting genuine market demand.
- We use P25 rather than median because sellers often achieve above-average prices — P25 reflects what a card consistently sells for, helping buyers spot good deals.
- If sold data is unavailable, we fall back to a median of active listings as a rough estimate.
Data Sources
🛒 eBay Browse API
Active BIN listings and auction data from eBay's official Browse API, fetched in real-time.
💾 Sold Listings Database
Recent sold prices in a D1 (SQLite) database, updated continuously. Powers all P25 calculations.
🎮 Pokémon TCG API
Set info and card metadata from pokemontcg.io, a community-maintained database.
📰 Beckett New Releases
Upcoming set announcements from Beckett's news feed, refreshed hourly.
🧙 Scryfall
MTG set listings and set symbols from Scryfall, the authoritative MTG card database.
Search Filters
- Sport / Game
- Restricts searches to the corresponding eBay category (e.g., Baseball → 213, Pokémon → Non-Sport Trading Cards, MTG → CCG Individual Cards).
- Grade
- Injects grading keywords into the query. Selecting
PSA 10appendsPSA 10;BGS 9.5appendsBGS 9.5, etc. - Card Type
- Multi-select. Appends keywords like
autograph,patch,rookie RC,refractor,numbered /, etc. - Year
- Appends a 4-digit year to the query, narrowing results to that card release year.
Public API
All endpoints return JSON. No authentication required.
| Param | Required | Description |
|---|---|---|
q | Yes | Search query (player, card name, set, etc.) |
sport | No | baseball · basketball · football · hockey · soccer · auto-racing · wrestling · mma · golf · boxing · pokemon · mtg · yugioh · lorcana · onepiece · digimon |
grade | No | psa10 · psa9 · bgs9.5 · cgc10 · sgc10 · etc. |
cardType | No | Comma-separated: auto · patch · rc · refractor · numbered · prizm · holo |
year | No | 4-digit release year, e.g. 2024 |
| Param | Required | Description |
|---|---|---|
sport | No | Filter by sport slug. Defaults to all sports. |
| Param | Required | Description |
|---|---|---|
game | No | Pass mtg for Magic: The Gathering sets. Omit for Pokémon. |
limit | No | Return only the N most recent sets (Pokémon only). |
| Param | Required | Description |
|---|---|---|
limit | No | Number of results (default: 20) |
| Param | Required | Description |
|---|---|---|
url | Yes | Full eBay item URL or numeric item ID |
Disclaimers
- Card Comp Search is not affiliated with eBay, PSA, Beckett, Panini, Topps, The Pokémon Company, or Wizards of the Coast.
- All prices are for informational purposes only. Market conditions change rapidly — always verify current prices before buying or selling.
- We filter obvious lot and supply listings, but edge cases may slip through. Use your judgment.
- As an eBay Partner, we earn commissions on qualifying purchases made through our listing links at no extra cost to you.
Contact
Questions or feedback? Email us at hello@cardcompsearch.com or find us on X (@thesethguycards).