My son is 12, will be 13 in just over 2 months. We just got him the 200 a month plan, which is what we all are on right now. Honestly, I am the one that is going to push us to the unlimited plan at this point. 
The reason we got DS a text plan is because I wanted to be able to text with him while he was with his dad for six weeks this past summer, and I just never canceled it. I like to be able to text with him, and so far I'm the only one he's allowed to text with. Well, that's not true - he could text with his dad, but so far they just don't. It's not a big deal to him at this point, as none of his friends text yet.

The reason we got DS a text plan is because I wanted to be able to text with him while he was with his dad for six weeks this past summer, and I just never canceled it. I like to be able to text with him, and so far I'm the only one he's allowed to text with. Well, that's not true - he could text with his dad, but so far they just don't. It's not a big deal to him at this point, as none of his friends text yet.