On big purchases, I never buy from someone who doesn't have a bunch of positive feedback and very little in negative feedback. If they just have a few positive feedback, I restrict myself to small purchases. I also tend to check out the previous auctions of the seller and it's feedback. If I am say buying a bike, then I like to see other bike items sold from that source with happy customers.

It's not that I'm worried about my money, more that I just don't want to waste my time.