It is quite clear from the OP that they are not into luxuries, Nigel. Do pay attention!
These topics ALWAYS generate the normal to the ridiculous. Yep, you can live in BKK for 20k... normal digs, liveable food, couple grand a week beer, the odd bit of strange here and there. Big budget guys lord it up (ooh, I can't live on 200k a month blah blah), but typically have loud cars, loud houses and high maintenance women. Don't do any of them. Have a beer on the balcony, get a motosai taxi to town and do not tip... EVER (they think you're a pr*ck when you do big anyway)! ????
Have fun!