I dont know what you are asking really Rick!
No one BUYS a killswitch.. theres no special kill switches out there (the link you sent looked like it was meant for something else, I cant imagine whacking down on a pot is either A) very efficient B) good for the pot.
Just buy any momentary switch, choose the one that looks good to you, as you say an old couple a video game switches would look GREAT, I think that in reality they are also in need of a hefty old THWACK I would go for the lightest touch you can find, quite large too. Unfortunately (as I have discovered when making mine) the bigger they are the further that they intrude into the guitar. You need a low, flush switch.
As for the circuit, theres 2.
Dependant on whether its a "Normally ON" switch, or a "Normally OFF" switch
anyway, YOU of all people know this, your Walker Glitch pedal is a bunch of killswitches right?
So, what was the question again?