Well, My bro got an unlocked 3G iPhone for $900. I guess that's good since iPhone is not released here yet.
I have been watching ebay auctions for a lot of time and I can say that $900 is too much. I am sure that with a little more research he can found it for $750
If you're looking for a selected unlocked iPhones on eBay... check out unlockediphones.net (yes, we own the site)... it provides aggregated and filtered iPhones from eBay, and similar information. If you want my personal opinion, I would be very careful about selecting your vendor on eBay if buying an iPhone... Rob