Check into an AT&T "Go Phone"; that's what I have; unlimited texting is not expensive there, you get to choose what options you have, you don't have to have a contract. My husband's Go Phone (he never uses a cell phone) is only $25 for 3 months/10 cents a call is subtracted out of it (since he only makes 1 call every 6 months most of the $25 gets "wasted", but it's only $8 a month so not too bad for emergencies.

I think I pay $25 a month for unlimited texting (and calls, etc.) and $15 extra for Internet. The biggest thing was the cost of my phone (a Samsung Galaxy with really good/big slide out keypad; I can't type text messages on screens well).