Use an escrow service.
I think AOPA might help if you happen to be a member.
I am a member. They quoted me $550 for their recommended escrow service. Do they take care of making absolutely sure the funds clear before completing the transaction? I ask because “I know a guy”, who took a fraud report from the bank I happen to use where they took a “certified” cashier’s check, said it was legit, cashed it, then 3 weeks later said it turned out to be fraudulent and withdrew the funds from their client’s account after the merchandise and buyer were long gone. Obviously, I want to keep this from even being a possibility.