They say they can accomodate your needs, so I imagine they can make systems for many players. I can not be sure of the pricing because they refer to teams without saying how many players are on each team. It is wisest to contact them rather than rely on my guesswork. This system is a a no frills basic kit. Its price is pretty low, even if you are in the US and must pay extra shipping charges from Canada.
Players activate buzzer with thumb.
It runs on a 6 volt adapter. Each player has a little box with a buzzer and a light on it. Everyone can see who rang in first. They sell several different models, so I advise calling and getting their brochures. Models for 8 - 16 players can be ordered and they rent out for weekends, as well.