Check the sellers feedback. This allows you to see the sellers history. Did they ship fast, pack products properly, answer questions quickly? etc. What's their over all feedback rating? Although not all eBay users leave feedback this can give you a good idea if the seller can be trusted. A good tool to use is this Feedback tool. It allows you to find out if the seller has any Negative feed back, if they do you can read the comments between the seller and buyer.