Are you looking for a smart phone or just basic cell phone?
I have the iPhone from Virgin mobile. It's a no-contract pay as you go plan. You pay the full price of the phone up front ($650), but the monthly charge is only $30, and you get 300 minutes with unlimited data and text. Additional minutes are 10 cents each, but if you find yourself going over, you can just get the $40/month plan which gives you 1200 minutes.
I got my mom a basic cell phone from Virgin as well. $20/month for 400 minutes.
Overall very pleased with the service.
In Japan. Heart surgeon. Number one. Steady hands.