I've decided to sell my 5S 16GB Gold factory unlocked iPhone. I realize it has 1.5GB of space left and I can't even update to 8.1.2 (lack of space). All I found was this site: http://blog.laptopmag.com/iphone-5-trade-in-value It's in very excellent condition. No scratches, nicks, or dings. Approximately what do you think I can sell it for?