if you need side windows too i have those:
http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/661044-factory-tinted-side-window-glass.html
if you just need the vents, you may need to call easy or parts heven.
the other option is to find someone parting out a car.
now.. only swb and targas had vent windows that opened. is that what you want?
or do you want the vent windows on 69-later coupes that were perma-shut?