I've bought loads of (expensive) stuff on Ebay and everyone has been absolutely A1 honest.

If you're in anyway dubious about something and there's a lot of money at stake, you can always just go and pick it up in person and pay cash on receipt of the goods. Chances are what ever you spend in petrol there and back will be along the same lines as having it shipped and insured. (Obviously this is fairly easy in the UK - Driving across the US might be a different matter...)

The thing to watch out for at the moment is the Western Union scam. People are listing completely bogus auctions, the content of which is just lifted straight from a genuine auction. They then only accept payment in the form of a Western Union transfer, which they claim protects you, but in actual fact is a dead simple way of them getting your cash without providing any genuine contact details such as their address. All the ones I've seen are pretty easy to spot though, as the seller has invariably only registered the day before, often in Canada.

Asking a few questions is a great way to spot a duff auction as well. If someone is listing gear that they have used, they should be able to easily answer technical questions about it.

On the whole the Ebay community is very honest and looks out for each other. If I see an auction that looks really suspect, I'll just mail the high bidder and let them know, as well as reporting it to Ebay.