Price in the smallest indivisible unit of the configured payment token, encoded as a decimal string. Must be a canonical decimal integer in [1000, 100000000]: no leading zeros, and a bare JSON number is rejected. The price is required for the fixed-price schemes (“exact” and “upto”) and must be at least 1000, the smallest amount the payment facilitator can settle ($0.001 for a 6-decimal token such as USDC), and at most 100000000 ($100 for a 6-decimal token). When the scheme is “origin_controlled” the origin server sets pricing dynamically and the rule carries no price: the field must be omitted — any provided value, including “0”, is rejected because it would not be enforced. Responses always encode this as a string and omit it for “origin_controlled” rules; the pattern matches exactly the set of values the server accepts.