Go the TMobile route. The coverage in COS is good, I got a phone for 20 bucks from their website delivered.
Then buy a 100$ card and activate it. Your minutes will be good for a year, and they add 15% more minutes. At 364 days, simply buy another card and activate, and your minutes roll over for another year.
It's a much better deal to get prepaid now unless you like browsing the internet on the can.