large sales on a bitcoin marketplace

[HanRuien]

How would an ideal sale on a bitcoin marketplace go down?
if it was something like a Yacht sale. 
I wouldnt want to transfer 2k btc to someone with the faith that they would produce. 
noone would be around to insure my transfer went through.
the yacht owner wouldnt sign the papers and mail them to me.  the only way to handle it is in person, unless theres a multitiered transaction that included a permanently held sum of btc that could be unlocked by the purchaser by completing the requirements of the transaction or redacted into the buyers original wallet. 
any way i can think it through would require a massive amount of trust in the other person.