Anyone remember Canarysun. His claim to fame was he bragged that he lived on 10,000 baht/mo in Pattaya. He walked everywhere, cooked at home, no booze, no AC, a treat for him was a 10 baht ice cream at KFC.
I'd say a single guy could live pretty well on 30K/mo for necessities as long as you had a side account for the unexpected and things like travel.