The main thing about vintage Ferrari's, Maserati, Alfa etc is these were just street versions sold to fund racing not to sell cars. Almost all of the track car is under the street version.
Race cars tended to be all alloy body and only a handful built. The price difference can be staggering especially with documented history. Street cars were fitted with interiors with steel body's and alloy closures.
The handling was night and day between equivalent years of American muscle. Many of the vintage 60's Ferrari's still handle better than cars produced in the late 80's (on 14" wheels and 70 series tires). This is an as built comparison.
On another note there are some American vehicles that demand high dollar. They to tend to be race derivatives GT 350, 500, Copo Comaro's , Lightweight Pontiacs and Fords.
Now with exotics your paying for the technology of race and design. Many supercars are over-engineered to keep the non pro drivers safe and on
road ex: the F430 understeer the race cars do not have. Plus all the other driver aids.
End the end it really is about two people wanting the vehicle to command a price.