Check out this Pop'n Music controller I made for $110.
Even has a stand!
Got the little table from Home Depot for $13
Got the buttons from
www.happcontrols.com for $97
used old Madcatz PS2 controller for guts
I just cut holes in the table with a jigsaw
soldered all the wires down
I am going to hook up the lights also, but I am not sure how to make them come on only when buttons are pressed.
If anyone wants any more details or knows how to wire lights, just leave a post here.