Buying
Hey,
Just a note: Paypal isn't flawless. They've hosed me twice now. If they get any glitches or security alerts, they don't call you. They assume the worst (sometimes, that's good, I know) and shut everything down. You then have the burden of proof of all sorts of things until they're satisfied, and in the meantime, your money is locked up. In one case, it took 3 weeks. In the other, they actually reached into the bank account that I transferred the money to, and took it back out! All sorts of problems arose out of that.
Anyway, my advice is to just check the references of a potential buyer/seller. If they're well-known, and have lots of references, you'll be fine.