I have kind of a dumb question. I really want an iPhone 4s for Christmas, but my service provider is T-Mobile. My mom says if I can figure out a way to use an iPhone on the data plan we have now, then she'll buy one for me (I also have to pay for half of the phone itself). I'm just wondering if I can buy a phone off of Craigslist or eBay and get it unlocked and then use it on T-Mobile, or if that won't work? I've been researching a lot but I can't figure out an exact answer. Factory unlocked phones seem to be way more expensive, and on Craigslist I see a lot of offers for phone unlocking for like $25. Could I just buy an iPhone for Verizon or AT&T and get it unlocked? I know that T-Mobile has a deal that if you bring in an unlocked iPhone without a contract they will support it, but the data plan for that deal is way too expensive, so I'm hoping I can do what I asked about above. Sorry if this was rambly and weird, but I'm kind of new to the technological world. Thank you so much!