and still make money ? ( remove all the functioning costs, rent marketing etc and see what would be left for the company)
Well, there's two things to take into account - in school, and in company teaching.
In company teaching in Warsaw is expensive - and the salaries reflect that. Sure, you can get a "native" without a clue for 50zl an hour, but any credible school which offers credible teaching will be charging close to double that. Take away even 75zl an hour for the teacher, and the school still gets 25zl an hour for doing nothing.
In school classes - let's say there's a group of 8, all paying 15zl an hour (which is about normal). That's 120zl an hour for the school - minus 60zl (school classes always pay a bit less) - still 60zl profit right there.
Then you consider that Polish teachers often work for far less money - so that subsidises the cost of a native, too. In Krakow, there's so many native "teachers" that the price has collapsed - but in general, schools can usually expect to take 25-30zl an hour profit from each class. It's not bad money if you think about it ;)
A language school can charge 110 zl an hour or more but how many clients would it get? And for how many hours?
It depends on a lot really - if you want a Cambridge examiner teaching you, then 100zl isn't that expensive. But of course, if you just want a 'native speaker' and don't care about the quality, you can get one for 50zl an hour without a problem anywhere.
This candidate shoudl keep us posted about how much he was offered ( he can also look for himself if they have a price list on their website and see what they can afford to pay him and still be in business...
I always did that. I remember one amusing job interview (that I went to because I wanted some interview practice and had no intention of working there) - I already knew they charged 62zl an hour for classes with a native speaker, so I asked for 70zl straight off. The look on their face was rather amusing.. :)
Like , pay depending on how many turn up for the class etc ??
Normal tactic of disreputable schools and should be avoided at all costs.