shop around I have a 16gb I am selling for $250 on craigslist and have a ton of people hitting me up for it. I said after I get the 5s it's theres.
You have a crack but you have one that is $200 more than mine. If the crack doesn't effect function of the phone and someone just going to put a case on it anyway then I think you could potentially get more. I mean it depends on your location and if you can find a buyer. Ebay is sadly the best place to go for something like that. They also take a big chunk of your profits. Try best buy/radio shack/apple and see what they will give you for a trade. It's your best bet as they will give you money up front and then just fix it. I wouldn't deal with ebay fees unless I had to