I know where to find them, np. But it won't be cheap, they're in high demand right now. Best to go during a weekday, not friday.
The major upside is you can meet lots of girls this way. Some might not even go for it the first night, but it can work for having something regular for a bit that won't cost too much ever time, especially since they're much freer than Sauna girls.
I'm guessing the karaoke room rental is about 200/hour, maybe about the same or up to 300 per hour per girl that accompanies you. Taking them home ought to cost around 1000-1500 if she goes for it, but it's really their own choice what they do.
Thinking of next some time.