The collector car market as any collector market, is quirky. Its not just about rareity. The rise in prices stated in the late 80's. I think a Superbird was about $20K and a Daytona was $30K. A nice Ferrari 246 Dino was $30K. I haven't kept track of Superbird prices. I have heard $250K. I think Dinos are $100K. A Superbird does have a race history. That adds to the price. A lot of those muscle cars took a dive in price, when the gas prices went up.
There are a lot of cars that don't command a huge price, but not a lot were made. Two that I own, '75 Bricklin, 3,000 and Saab Sonetts 10K. I think a Bricklin is $20K in nice shape. A Sonett $15K in real nice shape. The Sonett sold for $4K, the same as a Jag or Vette. A Bricklin $12K in '75.
I am not sure what from the late '70s to the mid '90s will grab collector status. I think the Buick GN or GNX is already there. Some Ferraris, the BMW M1 and some other exotics. I could see some of the Mustangs, the SVO, Mystic, Cobra etc. I could see the mid 70's Cobra gaining some type of following, but not huge price increase. I am also thinking the Jeep Comanche. OK, I own one. Still, it is starting to have a following. Again, not a huge price increase. I don't see X-body cars as a collectors cars. Then again there is the Ford Edsal.
Some I could see minor colletor status, Fiat X-19, TR-7 and TR-8s.
Tom