Unfortunately, individual sails come up for sale very rarely. Especially the Wildfire and Quicksilver ones - I have only seen one on the various marketplaces (Ebay, Gumtree, Facebook, CraigsList etc.) in many years. Boats with these sails are almost as rare but do come up very very occasionally.
Boats with Rainbow sails are slightly more common. There is one on Craigslist right now - although not close enough to you, I suspect.
1982 Laser Sailboat w/trailer in good condition. Clear/Notarized AZ title for trailer.
phoenix.craigslist.org
Individual Rainbow sails do come up for sale occasionally. You just have to keep your eye out - and be lucky.
Unfortunately, the last of these original "class legal" coloured sails were made in the late 80s, which means that any boat or sail of that age, or older may be in poor condition - but not necessarily.
Good luck with your search. I hope you are successful - and if you find more than one Wildfire or Quicksilver sail, please let me know, I would be interested too.
Meanwhile, here are some photos, gathered over the years to whet your appetite!