array
The expansions this product belongs to, as
{ id, name }. Usually one entry, but not always.
A Trainer Kit box ships two decks, and both are its expansions, so the field is an array
rather than a single expansion_id. It can also be empty. Such a product is still on
List products, but cannot be reached by expansion_id.Prices
array
USD, one entry per grade tier, each with
grade, price and observed_on. A sealed product is
ordinarily priced at ungraded alone. Empty when nothing is matched to it, never a null.integer | null
How many of this product sold in the trailing year. Depth of the market, not money: never render
it as a currency.
null means nothing is matched, which is a different fact from 0.