T-mobile full price iPhones on Apple's website are not officially unlocked, rather they're contract free. With that said, if one is to judge by past years then that phone does indeed come unlocked (which is different than buying a T-mobile iPhone from T-mobile's website or store).
I'm in the wholesale iPhone business (mainly ship internationally). Always looking for new buyers as well as providers. PM me if you think you have any leads (there's a finder's fee, of course).