I don't remember the model , the Ketron and the gamepad are in my car- i'll take a look next time I open it. I know it's a maxxtro gamepad for pc but i suspect that every pc gamepad with a 15 pin connector (not usb) will do the trick. btw footswitch may be the wrong word here. I hang it over the ketron and use it to get to these hidden functions in a single touch of a button.
the lowest price I found is 116$ for the FS6 and my gamepad has 8 switches.