Apple announced iPhone 4 today at WWDC. One of the most interesting bits is that AT&T is offering full subsidized price ($199 for 16 GB, $299 for 32 GB) to anyone who's contract is up in 2010. On a whim I checked, and yup I'm eligible. Cool, but I don't have $299 for an upgrade.
I previously heard about Gazelle.com on one podcast or another on Leo Laporte's TWiT Network. Gazelle.com is an online service where you can sell your used gadgets for cash. I checked it out. My iPhone has spent most of it's life in an iFrogz case, so it looks perfect to my eyes. Gazelle's offer for a good condition iPhone 3GS 32 GB is $274, and $304 for a perfect condition. The offer is good for 30 days, so if you sign up today and get your iPhone back to Gazelle by July 7th, 2010 you're good to go.
So I'm going for it. Will let you know how it goes as things progress.