Eventually, there will be a new pricing option made available for Best Buy that will be ready before the end of the big box retailer's current fiscal year. That would suggest that the new pricing plan would be in place before the end of February 2014. But for right now, a phone like T-Mobile's HTC One will cost $249.99 with a signed two-year pact at Best Buy and other national retailers. At T-Mobile corporate owned stores, you are asked to make a down payment of $99 and pay off the balance in 24 monthly installments of $20 each. And while you are not technically tied up with a two-year contract, your phone won't be unlocked until it is paid off.
The document does show that with the new pricing plan at T-Mobile corporate stores, over a two-year period you are still paying less for an unlimited data plan with the EIP pricing for an HTC One even though you are paying full price for the phone.
This leaked screenshot of an internal Best Buy document reveals the current pricing scheme for T-Mobile devices at Best Buy