hahaha You guys are making me feel bad for dumping all this cash on the phone. Yeah, I paid close to full retail for mine (32GB) on Craigslist. I didn't have to make a line, got to save around $100, and my favorite thing - got to haggle.
My upgrade doesn't happen till March of next year, at which point I will definitely be cashing in on the 4S and using the upgrade.
(P.S. I should also mention, I sold an iPhone 4 as well, which I had bought from the money I had spent on an international version of the Galaxy S II. I generally always have a couple hundred dollars "invested" on a cellphone.)