Obtaining 3g coverage when visiting USA

[Jeans7658]

I am visiting USA from the UK but have been unable to purchase monthly 3g coverage as Apple will only accept payment by credit card registered to a USA address with a zip code. I have visited 2 AT and T stores and 2 different Apple stores who tried to help but could not find a solution.
I can't believe there isnt a way around this. I would be very glad of advice. Thanks.