We have a big red button, not as fancy as the ones first uses. They aren't switch action or mushroomhead but its still a big red button.
We got it at a local electronics supply store for 5 bucks and its a alternate action (push once for on, push again for off) red pushbutton switch.
Very very nice
Look in digikey, mouser, parts express, jameco, other electronics catalogs they have them.
If you really wanna splurge and buy the big fancy ones they are quiet pricey