Any experience with Alltel "Pay-per-day" plans?

Like most kids these days, my daughter wants a cellphone. She mostly wants to send text messages, so I searched for “unlimited text messaging” and came up with an interesting plan from Alltel.

For 75 cents per day (about $23) a month you can get two of the following:

-Unlimited text messaging
-Free nights and weekends
-Unlimited mobile to moble (Alltel only)
-Favorite number (unlimited calls to one number

So I’m thinking that unlimited text messages and free nights and weekends for $23 a month would be great. But what do you do after the first month, how do you add more time to the phone? Does it have to be done by credit card or can you buy refill cards like you can with TracFone?

And does anyone have this sort of plan, are you happy with it?