That was a very expensive upgrade back then, and not a lot were sold. I think your best bet is finding a marker with one installed used...
Your best bet may just be here on the nation or ebay.
Do keep us posted, it seems like a very cool idea!
Hell you can probably find those all over the place on eBay or the sort.. just about any pancake noid from either a cocker, spyder, or Tippmann will work. How I think I have some for at my work as well