My son loves getting text messages. I'm not really into it and don't want to pay for it either.
My solution is to send him text messages for free.
WataCrackaz. It is an add-on for Firefox. Once you install it, you'll get an extra toolbar as shown below and you can send text messages directly from Firefox!
I send him text messages right from my roomy keyboard using Firefox.
I don’t need to mess with your phone’s cramped keyboard. And I can send messages to anyone without paying a dime. Of course, the recipient may be subject to charges for incoming texts.