Soi Buakhao beer bar prices why so different from bar to bar?

Did a little experiment on Soi Buakhao. Walked into 5 different beer bars in one night and ordered a large Chang at each. Prices: 89, 99, 120, 130, 150 baht. Same beer. Same street. Same night. The 89 baht place was packed, the 150 baht place was almost empty. Funny how that works. The girls at the cheap place were actually friendlier too. Just goes to show the flashy bars with the loudest music aren't always the best value.