So I'm considering buying a used unlocked iPhone 4 to use on Simple Mobile. I'm unsure how value goes down for iPhones, but considering it's the holidays, prices are a little higher than normal. The iPhone would have to be AT&T since Simple Mobile uses sim and micro sim cards on their GSM network (they use T Mobile towers). There is no rush to buy one, but I'd like to see about getting a deal, perhaps spend less than $200 used and in good condition. I priced them on eBay and they are at around $250 used (not unlocked). Would the iPhone 4s be at this price used when the iPhone 5 releases next year? Also, I want to see if anyone here has experience with Simple Mobile and the iPhone. If there is anything you guys could share with me about buying and using an unlocked iPhone, please let me know! Thanks.