I've had my 16GB Wifi iPad since Black Friday. I also picked up the Jack Spade Folio case for $69. I decided to take a look on Craigslist and found quite a few significantly cheaper than what I paid. For example, there's a 16GB Wifi + 3G for $525. I added up what I would get back on my return minus the restock fee and I'd end up paying approx. $50 more, but gain the 3G which I regret not purchasing. The question is, any experience with purchasing one used? Anything to ask or be aware of besides firmware upgrades? Any reasons NOT to go with a used device?