Wireless quiz buzzers

I'm looking for something like this
Quiz Show Buzzer System using Staples Easy Button

but wireless ... any ideas?

Do you want IR wireless or RF wireless?

In either case you have the problem of differentiating between all the different buttons.

For RF you could use different frequencies for each button or have the RF modulated with different frequencies. You would then need a receiver to determine which signal arrived first and energize the appropriate light.

Another way would be to have a transmitter and receiver in each button. The first button to transmit a signal would be detected by the other buttons and block those buttons from operating. You could have a light connected to each button to show which was pressed first.

A possible problem with such schemes is that it may be difficult to differentiate when two buttons are pressed near simultaneously.

But all in all it seems like a lot of work just to avoid running a few wires.