Sorry guys, but let's be honest: AT&T and T-Mobile are well overpriced.

For Phone-Only I normally get a Net10 phone from the nearest Wal-Mart, K-Mart or Target

http://www.net10.com/

10 cents anytime anywhere, activated in a minute and the last 2 years they even had Bundles such as Phone+Leather Case+Cigarette Lighter Cable + $30 Airtime for $29.99

I still have four or five Net10 Phones at home, as at that price (aka "free"), it's easier to get a new one on my annual trip, rather than recharging the old one.

Just checked their website:
They are now selling 750 Minutes for $25 - or a reconditioned phone including 750 Minutes (30 days) for $25
OR a new phone with $30 airtime for $25...