Then they might be fine for you. I find the pricing structure of these places a real mystery. However, they can be extremely cheap during the day, even as low as 100yen per person for the first hour with, perhaps, a drink thrown in for free.

At night they get more expensive. Whole groups of youngsters, out in the city after the trains stop running and with no hope of affording a taxi home, barricade themselves into these booths for several hours. Sometimes the prices seem extortionate but actually include an 'unlimited' amount of alcoholic drinks. Each place will have its own deals and incentives. However, how you'd work out what those deals are, I have no idea. Just walking past those places and seeing the gaudy adverts plastered all over the glass (and hearing what they pump out) gives me a headache.