I use a Virgin Mobile MiFi with my 16 gig, iPad-1 wifi only. Works fine, in fact, better than AT&T when in the boonies. (Sprint is the provider). My wife's iPhone loses all signal when deep in the heart of Texas.
I pay $20.00 a month for 1gig of data, when I elect to have the mifi active. Buying from WalMart. The device is slightly larger than a business card and about as thick as 2 quarters, stacked. Lasts 3-4 hours on a charge and came with a wall-wart and a cable to plug into a power port in the car.
Current price, online at WalMart is $129. (didn't notice where the original poster is located so, if this is not applicable, sorry.
regards,
J