Where I live (small tourist city) I pay 15PLN for the haircut (even with hair washing). I know Warsaw is more expensive, most of the websites show the price there 40-50PLN for men's haircut.
But here is cheap:
Men's haircut is only 10 zł.
Price does not include cleaning, which is performed upon request and costs 10 zł. We kindly ask to come with clean hair without the application of cosmetics, it will allow us to save time and your money.