biggles69's numbers are incorrect. To my best knowledge current drink price Dream Boys 450, all other bars in Soi Twilight and Tawan 350, Screwboys 300, Nature Boy 150, Super A 100.
Short time Dream Boys 2000, all other and Screwboys 1500, Nature Boy and Super A 1000.
See here as well (prices have risen since publication):
ChristianPFC - Adventures in Thailand: Prices in Bangkok gogo bars
ChristianPFC - Adventures in Thailand: Low season, drink prices in gogo bars