Selling my iPad (1st Gen)??!?

I have the first generation iPad, and I want to get the second generation now. I want to sell my iPad that I have right now, but I want to get the most I can get out of it. The screen is perfect, because I've been using a cover since day 1, and the backside is also perfect. It's a 64 wifi only version. Where would I get the most money out of this? And how much would I get?