We have done a few this year but it's interesting that the sales are always smooth until the very end. Usually the Bitcoin buyer tends to have second thoughts. However, we have started to use special transactions on the BTC blockchain that use cltv and htlc or hash time locked contracts. It's like a trustless or time-based escrow.

That means the buyer can deposit and rest easy knowing his funds are in escrow until he gets all the signed documents. When the documents are signed the seller waits until the time lock expires and viola! You have closed a sale.