2 MB 4g data $15/mth 5 MB $20 10 MB $25
When you hit the limit the data rate slows, but continues unlimited.
The one catch is that those rates are when you pay for a year in advance. Rates are higher if you choose to buy 3 or 6 months of service. They have an introductory deal where you can get 3 months of service as a new customer at the above rates.
I believe they still have a deal on Amazon where for $5 you can get a trial kit. They give you two sims. The first you can use for 100 mins of voice, 100 texts, 100MB of data to try it out. If you decide to sign up, you use the second sim and they activate it. I think you can also apply the $5 towards any of the regular plans at that time. It's worked great for me. I'm getting 70 Mbits download speed at home here in NJ, I've seen 170 Mbits at spots I've been in. A friend has it in CA and got 200 Mbits!