I just sold my iPhone 3G 16GB yesterday for $240 on eBay. It's jailbroken but not unlocked. I am just waiting for the payment to clear, so I should be sending it out by tomorrow. For a replacement I got a cheap little, uhm, I forget the brand.....it's just a little flip phone to hold me off for that week until I can get it in my hands. I will wait a couple days after release to actually go buy it, cuz I cannot stand lines. Maybe I can preoder it with AT&T? I'd rather buy it there, less crowds.
depending on what capacities the phone comes in, whether it's 16/32GB or 32/64GB I'll just buy the cheaper one, no need to overspend. This way I'll break completely even on a new phone @ $199 + taxes. Not bad saying my phone is 2 years old!