They are quite easy to make
i do a personal version, 2 buttons, so 2 times which can be altered. Powered by 1s battery (not supplied)
I do boards 10 at a time, each time i make alterations, the next batch will have buttons for 4 times
also working on a larger version for clubs, multiple times, remote control, lipo powered with speakers
£15 as part kit, email me for details
ronnie@g0njd.co.uk