When I was in the bar scene years ago, 150 baht for a lady drink was about average. Usually the girl got 50 baht of that.
Many lady drinks do not contain alcohol. Some girls don't want to be drunk all the time. Some girls also don't want to do P4P, they are content to make their money off the commissions.
It's a transaction, they are giving you their time in exchange for your money.
I never asked a girl to go with me. I waited for them to initiate discussion.