Why would you want/need 11-14 buttons per player? that's just silly.
Duh, he means 11-14 inputs per player. 4 for joystick, 6 for buttons, 1 for start and you are already up to 11. Whats so silly about that? Some Neo-Geo fighters now use 7 buttons too. Anyway a 4 player panel with this config and you are up to 44-48. Sounds like a valid inquiry to me.
Otraotaku, have you thought about hacking 4 PSOne DS pads and use 2 PS->USB converters? Used pads are $4.99 each at gamestop/ebx, and two dual-input PS2->USB converters would run you about $10 each, so you are talking $40 total and you would have the ability to hookup 48 inputs (56 if you hack the L3+R3 switches).