Verizon and Sprint are the only real options for acceptable coverage in the Plains. AT&T is a joke out here.
If you're only needing mobile Internet for chase season, your best bet is to decide on a service provider and data card, then purchase it on eBay for about 20% of what the provider themselves would charge you. This will also keep you out of the mandatory two-year contract most telecoms will hit you with if you purchase the device directly from them.
If you decide on Verizon, you should have no problem activating your own card on a monthly-basis without contract for $60/mo (plus an activation fee, of course). If you want Sprint, I'd recommend
Millenicom, who resells Sprint service on a contract-free, month-to-month basis. They even offer a $70/mo. plan without a data cap, which I've been quite happy using this season.
But regardless, if you're budget-conscious at all, go the eBay route for the card itself. I actually broke my data card (Novatel U727) a few weeks ago and needed a replacement quickly, so I logged onto eBay and seriously snagged one that night for $3.99 shipped. It arrived a few days later and has been working like a charm since.