Buyer and seller enter a smart contract where the buyer's funds are locked for two days, then freely recoverable by the buyer only after the contract expires. That proves to the seller that the funds exist at no risk to the buyer.

A day before the contract expires, buyer and seller meet up to inspect the goods. Upon inspection, seller hands over the goods and buyer validates the release order in front of him before departing, thus completing the contract before its expiration.

Infinitesimal cost, infinitesimal risk.