Late Christmas shopper here. I'd like to maybe try and get a used iPhone 5s for the wife. Looking for reasonably good value without locking into any multiyear service contracts. Is this an impossible dream? Or are there good sources for getting a used or refurbished device like this? I've never walked into a Sprint/AT&T/Verizon brick and mortar store in my life, do they sell the phones that people trade-in? Or are there good online sources that anyone here has used and could recommend?