I'm investigating taking a course in beginner Spanish in Mexico - I will be traveling from Arizona down to the Yucatan over the next 4 months. The courses I've read about are located in really urban settings - I'm interested in either camping or staying somewhere for cheap (either a homestay or hostel), and learning some Spanish off the beaten path. Any ideas?

This place has very economical classes and a great space in the forest with food included as well.
http://bosquevillage.com/en/languages.php

There is camping available as well as some cabanas.

A friend of mine loved her experience at this place in a small mountain town in Guerrero.

http://www.eltlatoani.com/

WOW! That Guerrero one is expensive! Almost $500 USD for a week. A friend is doing lessons in San Pedro for $125 USD/week with all the same stuff included. Not rural perhaps, but definitely cheaper.

OP, do you speak any spanish at all? if you go to smaller, off the track towns you will be forced to practice so that alone will help a lot. I got a Spanish-only speaking roommate for the same reason. I knew it would be too easy for me to slide by on English here in San Cristobal so I wanted to force myself to have to speak.

Ouch. I didn't even look at the prices.

You could try Valladolid, in the Yucatan. I've good things about study there.

You can study Spanish in Taxco, Mexico. Granted, its not really a tiny town, but it is quaint, an full of nice silver shops. Still, they'll speak Spanish with you if the overwhelming number of tourists won't.

Hola everyone,
I ended up doing the first recommendation - thanks!
But this link is better, it takes you directly to the language classes page:

http://www.jobutsu.com/raul

It was the least expensive option I could find, and my classes were completely one-on-one. There were two other students there but they were more advanced then me. Raul was really great, the location is amazing - rural like I was looking for. I totally recommend it.

-Z