Cooking classes in Bay Area
I too have tried to find Bay Area cooking classes without having to pay a huge amount.
So far my findings have been very scarce, but I did stumble upon this cooking site where you may view FREE cooking videos by typing in the recipe into the search bar, hope this helps you as it has me!
Thai cooking - I've been taking annual Thai cooking lessons in Oakland from Kasma Loha Unchit for the past 5 years or so (http://www.thaifoodandtravel.com).
Indian cooking - It's been a few years since I've taken a class from Ruta, but I would certainly recommend doing so. Like Kasma, Ruta also teaches from her home in Oakland http://www.rutaruta.com.