I had a '65 GTO, blue with a white convertible top and white bucket interior. Hurst 4-speed with four barrel carbs. It was in good shape when I sold it for $500 in 1971 or so. Now I see restored ones going for $40,000 all the way up to $230,000.
I put a $1 deposit on a one year-old Jaguar XKE that needed a new starter. The dealer was asking $1000. It was in fine shape. I was in school, though, and didn't have the money. 12 years later I'd buy a rust bucket of the same year for $5000, and spend 4 years and $12,000 in materials to restore it.