Ebay will take 10% or a max of $50 plus 3% for paypal. So you'd be looking at around $75 in fees. I tried selling mine on ebay for (a 32gb Wifi Black) model for 100 over list and got no bites at all. I don't ship internationally though which is where I think the bulk of them are going. Also, it would have to be sealed as as well for a decent premium.
I tried to sell two of them on craigslist, and got no reponses for either. Had the 32gb Wifi Black and a 32gb AT&T 3G White. Had both listed for about $75 over list. Both sealed boxes with receipts. They just sat there, not even lowball offers.
I ended up just returning both where I bought them from...
I'm starting to see some of the hard to get 64gb AT&T models show up on Craigslist now as well.