I have used H2O for years they are an ATT reseller. 3G service cost $10/quarter and the data is deducted from that at 5 cents/MB. Any money left at the end of the quarter rolls over if you put in another $10. You can get a years service for $100 and then start the $10/quarter if you use enough data that you want to build up a buffer. Phone calls are 5 cents a minute also if you use it as phone service. All the money you put in is available for the services you just have to put at least $10/quarter keep from losing your roll over account.
