You might want to check out
Virgin Mobile. It's 35 cents a min with no monthly contract and no system access fee. Just be warned that the money you put on your account expires after a certain amount of time. There's an option for auto top up though, so you don't have to worry about it running out on you. Check
here for more info.
I've had them for a few years now. I just put $100 on the account and I'm good for the year. It works out to just over $8 a month.