I have a TracFone - one of those 'pay-as-you-go' types.
I paid something like $40.00 for the actual phone (a Nokia model 5200), and about $150 for a years' 'reservation' of the phone line... the rates vary - the more minutes that you buy at a time - the cheaper it is. This last time, I paid $50.00 for 200 minutes - which got doubled to 400 minutes (because I 'reserved' the lind for a year). That works out to 12.5 cents per minute... I guess that's not too bad.
If I am out of my 'service' area, then I am considered as 'roaming'.
I went on travel last week to Phoenix, AZ - and drove back via IH-10. Along the way, I used my phone to call my girl-friend several times during the day. I got popped for 2 units/minute as I was roaming (.25/minute) - but it was worth it - and I got to talk to my sweetie.
I may get a 'real' phone someday... but for now, this one meets my needs. It gives me a telephone away from the landline, and works pretty well. Service is through AT&T - I have no connection problems... or not any more than T-Mobil (the other provider that we tested on our IH-10 adventure). The only place that I had a problem was in a rest stop just outside of Phoenix - when I had a very weak signal, and the call got dropped.
The main thing that I like about my choice - is that I have only invested about $230.00 since February 2005... or that works out to about $40.00 per month (taxes included). I can live with that.