A switch box like this can be easily made (and more cheaply) by using either a 6 pole double throw relay, or three 2 pole double throw relays that have 12 volt DC coils. A small 9-12 volt DC wall wart can supply the power for switching the relay. Solder the inputs and outputs to the relay, add a power switch that switches the power to the relay's coil, and you're good to go. I'm sure this is how the switcher box above is made.
[This message has been edited by soundhound (edited February 26, 2003).]