Value tracking
CardboardChasr keeps your card values fresh using eBay’s public Browse API. Here’s what it does, what it doesn’t, and how to tune it.
The formula
For every card we refresh:
- Build a search query from the card’s metadata (year, brand, set, player, #, grade).
- Query eBay for up to 10 lowest-priced active listings matching that search.
- Take the median of the lowest 5 asking prices.
- Write that to the card’s
current_valueand log a history row with a confidence score.
Active listings, not sold comps
eBay’s public API only surfaces activelistings. Sold-comp data (what cards actually transact at) is gated behind eBay’s Marketplace Insights API, which requires a separate application and stricter approval.
Active asks are directionally accurate but typically run 10-25% higher than sold prices. Use the value as a market floor estimate, not a guaranteed realization. We may tune the formula with a scalar once we have enough data to estimate the gap.
Confidence buckets
| Badge | Criteria | Trust it? |
|---|---|---|
| high | 5+ listings, prices cluster tightly (CV < 0.5) | Yes |
| med | 3-4 listings, or 5+ with wide price spread | Reasonable, sanity-check against eBay |
| low | 1-2 listings (small basket) | Treat as a ballpark only |
Rate limits
CardboardChasr uses a shared application-level eBay API budget (5,000 calls/day). To keep things fair:
- Each user has a default daily cap (100 lookups/day). Resets at midnight UTC.
- Nightly cron uses up to ~4,500 calls/day across all users, leaving ~500 headroom for on-demand clicks.
- The “Grade Now” live-comps lookup costs 2 calls (PSA 10 + PSA 9 searches).
- When you hit the cap, the feature tells you and waits till tomorrow.
Settings
Head to /settings → Value tracking:
- Enable eBay value lookups — master toggle. Off = no eBay calls on your account.
- Auto-refresh cadence — Nightly (runs at 03:00 UTC daily, recommended), Weekly (future), or Off (on-demand only).
Raw cards are always on-demand only — use the “Estimate value from eBay” button on the card detail page. The algorithm for raw-card queries is noisier than for slabs (grades act as a strong filter), so we don’t burn your cron budget on them.
Grading EV: live comps vs multipliers
On a raw card detail page, the “Should I grade?” block uses default grade multipliers (PSA 10 = raw × 4, PSA 9 = raw × 1.6, etc.) to estimate graded values.
Click “Use live PSA 10 / 9 comps” to swap those multiplier-derived estimates for live eBay asks on the exact same card graded at PSA 10 and PSA 9. The EV calculation updates in real time.
Grades 8 and 7-or-less stay multiplier-derived — they contribute little to EV and searching 4 separate grades per card gets expensive. If that assumption matters for your collection, let us know.
Troubleshooting
Why does my Wemby show $X when sold comps say $Y?
Active asks run higher than sold prices. Our number is a market floor from listings, not a transaction average. Cross-check eBay’s sold-listings filter for the actual sold median.
Why is my raw card’s estimate so different from my graded version?
Raw searches match any condition and can sweep in altered or low-grade examples. The “Raw lookups can be noisy” label is there for a reason — treat it as a ballpark and don’t rely on it for insurance-level accuracy.
Can I pin a specific eBay listing as my card’s comp?
Not yet. We use search-based aggregation because pinned listings end and go stale. Ping us if this matters for your workflow — it’s on the roadmap.
I want to use my own eBay developer keys for higher quotas.
Not available yet. If you’re regularly hitting the daily cap, email us — we’ll raise your ceiling or prioritize the “bring your own keys” feature.