Learning Thai

[davu]

My wife speaks good English but is not really capable of teaching me Thai, she just shrugs her shoulders when I ask a question.
So bearing in mind that I scrape along financially, where can I take a Thai course that doesn't just consist of learning phrases and doesn't cost $20.- an hour? I have got the Thai alphabet more or less sorted out and can read stuff like 'Chang Classic', 'Diesel' and place names, even some of the subtitles on TV.
Did I read somewhere that a university in Buriram does stuff like this?
As a subsidiary question, would doing an ED extension be easier than a marriage extension? I should have thought so?