How much does it cost to go to the average bar in Bangkok? (I know the tourist bars are expensive.)?

Actually most bars aren't too expensive, there's a lot of competition in Bangkok. Some of the hotel bars and trendy nightclubs can be expensive though. An average bottle of beer will cost 90-100 baht, a mixed drink will be somehwere around 120 baht at many places. A lot of the pubs will have happy hours and specials like 2 for 1 on certain nights. There's a local bar near where I live in Bangkok that sells 630 ml. (large) local beer for 55 baht, but that's about as cheap as you'll find. Imported beer can be expensive, but Thai beer is pretty good and well priced. Cheers.