Bike's from the eighties are in a weird transition time because they are not really collectables and they are not new either. For this reason, the market for eighties era parts is not really matured or well organized.
Probably the best place to find eighties era bicycle parts is on e-bay. See
http://listings.ebay.com/aw/plisting...294/index.html
You could look under "Collectables/bicycles" as well.
Good luck.