Probably your salesman would have to be trusted enough as the escrow. Buyer pays salesman/escrow, salesman/escrow tells you to push domain over to buyer, buyer authorizes salesman/escrow to release funds to you, salesman/escrow sends you the amount -10%.
Yes, also, god forbid I treat this like a real business deal unlike most others on this forum. I would have his/her real information....when they make a sale, they send say 50% of the BTC and then I push it to client. Then I get remaining. The person who desires the domain product pays first generally...so if the person doesn't give me the money or a portion I won't push the domain over thus he looks like an ass. Lol