i did this same project, i used the x-arcade stick someone posted above (minus the trackball), it's a fantastic piece, works great.

i found out that to build a cabinet was gonna cost me about $80 in materials, so i went a different route. a local arcade vendor here sells old empty cabinets for $50 each, i got an old gutted Gorf machine and modified it to find everything, worked great.

i agree with finishing the cabinet before you start playing it, my still isn't finished, it needs stickers and paint touch-ups.

good luck.