supposedly that site has gone down the tubes recently with the influx of new customers due to street fighter iv. but ya the same creator of that board makes one for wireless ps3 controllers. so with a bluetooth dongle you could even make this wireless ! I have a wireless arcade stick utilizing this technology and its great.
i think theres an assembled one on ebay for 55, which is inflated, but its in stock.
i've been thinking about making a custom interface for web browsing. like a joystick for scrolling and buttons for various things. making the encasing is the hardest part.
I once did the research to build a USB Keyboard out of 24mm Sanwa buttons, before I realized it was kinda dumb and super duper expensive. Theres a website out there that sells 100+ key usb keyboard pcb with easy connections for buttons. It was $130 if I recall.