It all depends and is highly variable.
I've found the between 15k and 100k!
Plenty of Malaysian/Thai/Viet at the low end. Russian in the middle to top half. The occasional stunner at 100k.
Much of the girls 'working' are bar scam girls and just to take you to other bar to have your credit card run up.
Discreetly ask if they are genuinly working early on, if they are - you'll find them honest. The scam girls will tell you all about their friend who's running late/hasn't turned up and 'lets have a drink together' whilst being all touchy with you - don't be fooled, you won't be scoring with them.
Whilst I'm out, I usually sway past Rigoletto, that's usually a meat market and can usually pick up for free - local JP girl gaijin hunting