Just for the hell of it, I put my 32gb 3GS on Craigslist for $550 to see if someone will bite. There's been a few on there and on eBay that have gone for even more, so it someone will take mine for $550, then I'll be able to get the iphone4 for no money out of pocket after taxes. That'll work for me.
If not, no big deal, as the new iPhone isn't that big of an upgrade over the 3GS to be worth spending money on it for me. The main upgrades that I'm interested in are the software upgrades, which I'll get with an update.
What are the cxl fees these days? buy phone, cxl contract, sell phone.