I know there's the 1520.1, .2, and .3...Which one would I purchase if I used T-mobiles towers? And rather than new, is there a possibility of a used one? I happened to get my mint 925 for 180. Thanks for any help!
No. The AT&T one (RM-940) would work on T-Mo poorly, BTW. It's missing 1700 MHz on the 3G/H+ radio which is a must for T-Mobile... Any area not refarmed for LTE and you would drop to EDGE speed.
B&H Photo website had the best price I could find when I was looking. Try a web search for "Buy Lumia 1520.3" and just make sure it is the RM-938... I've seen RM-937 come up on that search and it is not LTE compatible with T-Mo.