How much would you roughly need if you are there for 2 months?
This is my friend's blog. He's currently in Chiang Mai training at Team Quest Chiang Mai and updates his blog regularly. If you have any specific questions you can just ask him on his blog. He's usually pretty good at responding and pretty informative. He's been living and training in Thailand since 2008. Given this blog post about costs of training is 2yrs old, it should give you an idea of what the general range of costs are:
http://www.myfightcamp.com/2011/06/actual-monthly-living-costs-training.html