as far as the 30K it is def doable but u will lead an extremely simple life. I think alot of westerners move to Thailand because they love to travel and your not going to do much traveling on a 30K salary. .
I have a friend who is a Philippine english teacher and he makes 22K. . he lives but he is real frugal and doesnt travel much or go out much. .
plus what mvinci said. . it depends where u live. . i dont think u can live on 30K in phuket, BKK ect. . maybe in a more rural area it is possible. .