I see a lot of people on eBay selling unlocked and jailbroken iPhones for 650+. I know how to do the unlocking/jailbreaking part, but wonder how people buy the iPhone 3Gs without a contract to resell. Anyone know? I want to tap the market.

you can buy them off ebay.. att store, apples website, or off of craigslist,,. usually craigslist has the cheapest