need help buying an unlocked galaxy s5

[maxwell max]

ok heres the deal. this stuff is pretty much over my head when it comes to phone compatibility and everything. i am trying to buy an unlocked s5 for my girlfriend for xmas, we live in new york, united states, and we use walmart family mobile, which is through T-mobile. there is all kinds of differnet model numbers, ie. g900A, g900h, g900f. i have read that the g900 f is the model i need for the united states and to be able to get 4g. anyways, any help would be appreciated. i guess the main question is, what model of the galaxy s5 should i be buying, and does anyone have any suggestions as to the most reputable sources to order one for a reasonable price. and oh yea, it must be brand new in the packaging or she will have a fit thats just the way she is

 

[Ollie]

If the network feeds off of TMo then I would just buy it from TMo and pay 30 bucks to have it unlocked from a cell unlocking company.