That was just posted two days ago, nothing has changed.
You also misunderstand on the $30-50 comment. That's the minimum most providers want to charge you for service with any real amount of data. That doesn't mean that you'll get 3-5GB of data for $30-50.
The problem with T-Mobile is that most areas are going to be 2G data coverage once you get outside of any major metro area, and they're on oddball data bands (this partyly rules out Spot as well). Some band juggling is happening and they're putting some of their high-speed data services on the 1900MHz band, but it's not a full roll-out. As such, an AT&T MVNO is the best option with traveling... but good luck getting a price break there. They've lowered their data prices, but their prices are still restrictive. Aio's literally going to be the best deal per MB, but if you don't have a tablet, you're in for at least $55 with a smartphone.
You can do 3-5GB of data from AT&T directly for something like $30-50 (IIRC), but again, it's heavily device restrictive (no smartphones), tablets and USB modems only.
Best advice? Try not to need mobile data if at all possible.