When we made a cross-country move back in 2006, one of my wife's friends insisted that she needed a cell phone and bought her a prepaid. It lapsed, but we reactivated it for the next move three years later. We now keep it up for $30 every 3 months and use it for emergencies and trips. It costs that much to keep the service active, but the minutes are almost never used up.
Continuing to not carry and use a phone everywhere is partly a matter of stubborn pride by now, but it's also financial. I already pay $100 for phone and internet service, and don't see the need to pay another, what, $200 per month for more phone service. That money will go into my kid's college fund instead for as long as I can hold out. The home phone lets me talk to anybody I need to, and the net connection already allows me to work, read, communicate, shop, and waste more time than I need to.