I've only had experience buying unlocked GSM phones from large eBay stores. I was thinking of getting a Garminfone for $300ish on T-mobile but most of the sellers don't have their own eBay stores and are just small time sellers with less than 100 feedback and such. How do I make sure I'm not getting a stolen phone? I hear a lot about ESN numbers for CDMA carriers, but what about GSM phones? Do they have theft protection that bricks the phone as well?