I got my my first gen 32gb iPad Wifi + 3G from someone on Craigslist for $250.
I found out the previous owner extended the warranty because the 3G antenna was cracking. I took it to Apple, and they said it was absolutely covered under warranty. The guy took it in back, came out, and handed me a shiny new Refurbished iPad in plastic wrap.
Best Craigslist deal to date. It's the lowest I've ever seen. Ever. Period.
The refurbs on Apple.com are a great bargain regardless. I'm a cheap-o, so it's all about cost for me. The A5 chip, cameras, and a different housing aren't worth another +$250 to me.