usally someone with alot of positive feedback is someone you can trust. But good sellers all have to start out at 1. If you pay with paypal your guarenteed upto 500 dollars back. I've bought a couple of computers and various parts from a bunch of different people. It's a pretty safe place to buy/
As a seller and as someone who has considered buying computers on eBay, here's some advice. EBay is overpriced. I've bee nseeing 1.0ghz eMacs going for $900. I sold an old iBook for $500 more than I paid for it. If you want a good rip off, then eBay is your place.
I have a fever and the only prescription is more cowbell.