I went to Siam Rice Cookery! It's lovely! The teachers were very nice and helpful. And the food I cooked, under their coach, of course, was so delicious!
We have recently been to Chiang Mai too and loved it pretty much. 400B is quite a lot - but as everywhere in SouthEastAsia police officers try to get the most of tourists. Where about in Chiang Mai have you been for the cooking course?
Chiang Mai really turned out to be a good place for many Westernes to settle down in Thailand.