Value and liquidity answer different questions
Value asks what an item may reasonably sell for under supported assumptions. Liquidity asks how readily, frequently, and consistently a buyer may appear near that amount. A valuable card with a narrow collector base can be less liquid than a modest card with steady demand.
Combining the two into one score hides tradeoffs. A reseller may prefer lower-value inventory that turns predictably, while a collector may accept a slower card because it fits a personal set or team goal.
Use demand evidence—not popularity invented by a model
Useful eBay liquidity evidence can include relevant comparable-sale frequency and recency, price consistency, active competition, and sold-to-active relationships when legitimately available. Each signal needs clear provenance and identity matching.
A name-recognition claim from an image model is not market demand. Player or Pokémon popularity should come from permitted demand evidence or deterministic reference data, not free-text confidence.
Active supply is not buyer demand
Many active listings can mean a healthy marketplace. They can also mean that sellers are competing for too few buyers or asking too much. Active count is therefore a market-presence or competition signal, not proof of sell-through by itself.
When completed-sale coverage is missing, label the limitation. Do not convert active supply into an invented demand score merely because it is the only available number.
Include transaction count and labor
A lot with twenty individually sellable cards can have diversified value and still require twenty listings, shipments, buyer interactions, and opportunities for returns. Expected transaction count and labor belong beside liquidity, not hidden inside value.
Bundling by player, team, set, or treatment may reduce transaction count at the cost of a lower combined price. That tradeoff should be modeled by resale channel and strategy.
Use liquidity to shape—not rewrite—the decision
Liquidity can influence ranking, risk reserve, expected holding time, and channel recommendation. It should not rewrite the underlying card identity or turn an unsupported value estimate into a supported one.
Keep value, liquidity, confidence, freshness, preference, concentration, and effort separate. A strong decision can then explain which signal creates the opportunity and which creates the risk.