After blowing past Sprint in the last quarter, T-Mobile is still pulling out all the stops to increase its subscriber numbers. The latest announcement is a new family plan with 10GB of non-shared data per line. The price varies based on how many lines you have, but the sweet spot is four at $120 total.
If you enroll in T-Mobile's new family plan, you pay $50 each for the first two lines. The third is $20, and the fourth is free. That averages out to $30 per line, but you'll need to sign up before Labor Day (September 7th) to get the deal. You can keep this plan as long as you stay on it, though. You can double the data bucket for any line to 20GB by adding $10 to the bill as well.
As with all T-Mobile plans, this is just the high-speed data allotment. You technically get "unlimited" data at a slower speed. It also includes all of T-Mobile's recent Uncarrier deals like Data Stash and coverage in Canada/Mexico at no additional cost.