I'm currently using an unlocked iPhone 5s 32GB (T-Mobile) and I got it outright (paid upfront) at an Apple store last year. All the deals and trade-in offers I see are for plans with a 2-year contract on them. My question is: what is the best way to trade-in my unlocked iPhone 5s 32GB and get the iPhone 6 (smaller model)? I paid about $900 for the phone and AppleCare+ so the carriers' trade-in offer of about $300-350 do not look too attractive to me.. Thanks!