Until someone has a reputation, it is hard to extend trust. Sometimes it makes sense to share the risk and split up the transaction into 2 or more parts, e.g. pay half, ship half... then if satisfied do the second half and give them feedback. I tend to be more trusting for $100 or less.

I should note however, that several times, ebay fake users locked up my auctions. They would create an account and 10 mins later make an offer for the Buy-it-Now price. But they would never actually pay. I would have to wait for 3 full days until the fake transaction timed out and I could relist. Nothing I could say or do would convince ebay that it was a fake user. It happened enough that I had to switch to make buyers pay immediately when offers were accepted.

The crooks would only attack the most expensive goods and were trying to get people to ship goods before payment I guess. They must succeed some of the time as they keep trying. Ebay does not care that they allow millions of fake users (machines) create accounts and muck with real people's auctions.

Sorry for the Windy reply!!!