Talk to fire-bug on this site.
He has a supergun thread in the hardware section. Its a one box solution that does what you need. PCE FX thread is helpful if you want to build one yourself of course
I think what your failing to realize is that the PCB needs power to operate, it needs a harness to connect to, and it also needs to receive input commands from joysticks and buttons. Your looking at $100+ for a supergun (I don't know what fire-bug charges).
It helps if you have some kind of joystick/controller already. Fire-bug can make a supergun that takes a whole host of different controllers, but you have to select just one to use. IE you can't plug a SNES pad into the supergun if the supergun is wired for Playstation perhipherals. But you can use any playstation peripheral with it.
This industry has become 2 dimensional as it transcended into a 3D world.