Or maybe they should make a system that activates the iPhone 4 to you (after doing a check in China's database that you actually live at that address) in the store, so when they take it out and try to sell it, all the user's phone bills come back to you, the scalper.
The only way to get around this is to jailbreak the phone, but that can be sidestepped by requiring phones with certain serial numbers to check every time they have an Internet connection for the latest version of iOS.
If certain phones report that they've been hacked in the upgrade process, then the phone turns into a brick.
Post this outside the store in big letters and that'll shut 'em down.
Or you could take the simpler route and just restrict new purchasers to buying one iPhone per year.