This is great!

Thanks so much for sharing the code, it's extremely helpful.

I've thought about making something similar (notifications for certain events via SMS) and I'm wondering if you know if Twilio can charge a fee to the end-user for every text? i.e. if for example I say "Subscribe to get an SMS every time there is a tornado in your area, for 50c per SMS" (I made that up, BTW)