But I don't think there is such a site.
Too many factors are always changing.
Depending on the state of the models, the kind of cars, the rarity, the always differing demand because of re-issues or better new models of the same kind.

Best is, checking ebay for similar cars, bookmarking these and see if they sell, and for how much.

Also, do you need it for just knowing or insuring these, or to sell them?
You could also post a list or at least some examples here, to see if they are sought-after or just of personal sentimental value.