Yeah, buying cars can be a bitch...... You just don't know who you are dealing with, which is why I think people continue to buy from dealers - At least that way they KNOW the bloke is probably a crook.
But seriously - your mate should at least try to get some money back for the cost of the plane flight cancellation charges etc.
A while ago I had a run-in with a bloke who tried to sell me a 1200 ute with a -just-about-to-shit-itself- CA18DET, & when I pulled out (due to the stuffed engine) he kept my deposit ($400) - 8 months down the track I had my small claims hearing & got my money back!
I'll admit the court system is a long drawn-out process, but I got there in the end + learnt a bit about the legal system in the process.
The one thing that people kept saying to me though was "Caveat emptor", which means buyer beware & is more or less how private purchases should be veiwed.