If you've got the equipment, it's probably easiest to just build your own. The only thing I remember being a little tricky to find is the t-molding cutter, and that I was able to get online. Doing it yourself also means you can set things up like stick alignment and button pitch exactly the way you want it.
Were you looking for something pre-wired as well, or just the box?
You basically need a spade bit for buttons and joystick holes and a slot cutter and router for the t-molding. My boxes were always built into the cabinet itself as you can see in the images so all I needed was the panel.