I use a pandora's box for one of mine. Isn't hard to wire up. I got everything through Amazon and ebay. There's seems to be a new Pandora's box. These are the parts you need. You can find some cheaper on ebay like the harness and power supply.
Buttons and joysticks I bought from Focus Attack and Paradise Arcade. Both are reliable places. Paradise seems to run out of certain colors of buttons more often though. I'm not a fan of the button and joystick kits on amazon and ebay. They're good for a first timer since you get everything you need but if you want good arcade style buttons and joystick and feel you need to buy them separately along with the switches.