At T-Mobile's "UNcarrier" event, the company has listed the phones it will sell that include LTE. One of the most important on that list the Samsung Galaxy S4, which T-Mobile says is launching on May 1st. Despite the carrier's claims to being radically more open than other carriers, the Galaxy S4 (and other phones) will be locked — at least until it's paid off. The Galaxy S4 will work on T-Mobile LTE network, which is currently live in seven cities.
Although Samsung's phones have been important to T-Mobile, the main hardware focus of the event was obviously the iPhone 5, which T-Mobile will begin offering on on April 12th for an initial $99 outlay along with a monthly $20 payment plan. That's the same price the carrier will be charging for both the HTC One and the BlackBerry Z10. Unfortunately, T-Mobile didn't specify the exact price of the Galaxy S4, but it wouldn't be out of the realm of possibility to see it arrive at the $99 price point.