I saw one at a truck stop marketed to truckers, dont know if it had a yearly option, but it was costly compaired to going with a contract. Slingshot mobile is the company. Up front cost was expensive, about $300 and service is $55/month. Looks like it uses the Sprint network and does allow off sprint roaming. Cricket has prepaid data for $40 in most of their markets, but only works in Cricket areas, no roaming. I think best bet would be to buy your own equipment and activate it with one of the nationwide carriers. If you bring your own equipment, there's no contract, and most will average ~$60/month.