Probably a decent amount, but you never know. I picked up my 3g yesterday and am selling my launch 1.0 8gb on ebay now (I didn't unlock it, but it's got v1.1.4 software). I've got a couple days to go and it's at $200, but not uncommon for the 8g's to go for 300-400 sometimes fetching more if unlocked. Of course, it would also depend somewhat on what comes with the phone. I have literally EVERYTHING my phone first came with including the shrink wrap and little plastic cover things for all of the accessories so that adds some value IMO. My phone is also in mint condition. So keep all that in mind. Just do an ebay search for your phone and check off the "completed listings" option and that should give you a pretty good idea what you'd get for it.