Use the advanced search function to narrow down results within so many miles of your zip code. You can then check the bike out before bidding on it and pay for it in person. That's the only safe way to do an ebay transaction for something big like a bike or car.
It's also not difficult to figure out which bikes are scams and which aren't. First off, anyone who thinks they can get a mint custom Busa for $3800 is a blithering idiot firing on half a stem cell for a brain. Another clue is the pre-approved bidders list in which you have to email the seller to get on, if you see that it's automatically a SCAM. After contacting the seller you get the typical line of how the bike is in another country (relative died) but he'll ship it to you free of charge.
Hard to believe anybody could be stupid enough to fall for it at that point but it must be working because there are so many of the scams up at any given moment.
The stupidity really is out there too! All those accounts the scammers are using are hijacked from legitimate users. Those legit users were stupid enough to fall for fake ebay emails asking for account passwords and credit card info.
Since there are so many hijacked ebay accounts I'd imagine there are just as many tards sending out $3500 to $4500 on the Busa deal of a lifetime!