How CardStock calculates card box prices
Which shops we track
CardStock tracks the public listing pages of Canadian and US hobby card retailers. A shop counts as tracked when its catalog is collected on our nightly schedule. We do not track marketplaces with per-seller pricing, with one exception: eBay listings appear as clearly labeled fallbacks when no tracked shop has a product in stock, and they are always attributed to eBay. The retailer directory lists every shop we cover.
How often prices are collected
Shop catalogs are re-collected nightly, and derived statistics are rebuilt shortly after each collection pass. Pages that show a “last checked” date take it from the rebuild timestamp of the underlying data, not from the page render time.
What “lowest price” means
A product's lowest price is the cheapest in-stock listing we observe for its standard sealed unit: the hobby box for sports card products and the booster box for Pokemon. It is the shop's listed item price in the shop's own currency. Shipping and tax are not included, because they vary by destination. Special editions and store exclusives are tracked separately and never supply the headline price of the standard unit.
What “median lowest price” means
The median lowest price for a group of products (a sport, or one season of a sport) is computed by taking each product's own lowest in-stock price, then taking the median of those values. It answers “what does a typical box in this group go for at its cheapest shop?” It is a different statistic from a single product's typical price, which is the median across the shops carrying that one product.
Canadian and US prices
Canadian and US shops are measured separately, each in its own currency. A Canadian price is always CAD from a Canadian shop; a US price is always USD from a US shop. We never convert one market's price into the other currency for display. Where a list must be ordered across both markets, ordering uses a currency-normalized value internally, and the displayed amounts stay native.
What gets excluded
Sold-out listings never feed a current price. Listings priced at or above $100,000 are treated as “call for price” placeholders, not prices, and are excluded from aggregates. Listings we cannot confidently match to a catalog product are held out until they are resolved. Operator review runs continuously on the matching between listings and products.
How deal scores work
A deal score measures how far a product's cheapest in-stock shop sits below that product's reference price: the median across its shops when three or more carry it, otherwise the product's own recent typical best price. The score is weighted by how many shops carry the product and how tightly they are priced, so a single outlier shop cannot fake a discount. Canadian and US shops are judged in their own market.
Price history
We record prices as observed on each collection date. Historical series are a record of observations, not a continuous market index; days without a collection carry no data point.