Ebay is a great place to look for some vintage tech. Have a look at this CD duplicating robot that TINYenormous got for only $11. Instead of ripping out and replacing the control electronics he lucked out and found someone who had details on converting it to serial control.

 Thanks Ross.

"I bought it intending to put an arduino in the place of the control board and probably have to do a lot of reverse engineering. The next day I happened upon this site where, amazingly someone has already opened one of these up and has instructions on how to enable serial control! I still am in awe of how lucky I got and really happy that DarkBane dropped all of that knowledge on the world."