I've done long distance sight unseen deals before. On my X2 most recently.
If cash isn't an option which is the case in a long distance deal then just run it through your bank and theirs.
Each of you instruct your bankers on the same terms for funds transfer. IE. they tell their bank to release the funds by wire transfer once given the go ahead by them, after inspection. You tell your bank to confirm the wire transfer before saying bye bye to the boat. Simple, safe. The bank will know they've received legit funds. Then you will be assured as well.
If either party isn't willing to do this then something is fishy.
'06 X2 MCX
"I understand why some people may not want to do this the way I have recommended but I can't understand the death grip some people have on a toilet plunger with a hose fitting." -JimN