BTC/Ethereum/LTC aren't really a good option since the value fluctuates so much, but there are cryptocurrencies (stablecoins) that are tightly tied to the USD and only vary in small fractions of pennies from moment to moment - two examples are Tether and USD Coin. For a transaction that takes place quickly (buyer purchases crypto, transfers to buyer, receives item, buyer cashes out crypto) any of the less volatile currencies would be fine.

BTC/Ethereum/LTC aren't really a good option since the value fluctuates so much, but there are cryptocurrencies (stablecoins) that are tightly tied to the USD and only vary in small fractions of pennies from moment to moment - two examples are Tether and USD Coin. Of course, this requires you both to have at least a basic understanding of how to buy and sell crypto.