When I bought my car in New Jersey and shipped it to The Netherlands I used a escrow service the shipping company offered. This cost me 500$, but made it a safe deal for me. The owner of the Delorean got a check from the guy that came to pick up the car, after inspecting the car and title.
Before the pick up some paperwork had to be made, but nothing dificult. I think a bill of sale with a notary stamp.
I have bought 3 cars over the years in the USA and never had any problems. Some sellers are not willing to deal with overseas people, that is up to them, I just find sombody who has no problems with it. 2 cars I got in contact true Ebay, but never had the high bid. Just contact them later if the car didn't sell and agreed on a price.