I would agree with your general theory, but your scale is way off. The cars you mention are going already be worth tens or hundreds of thousands of dollars, except for 3), which would be a once in a lifetime incident and thus even more rare.

This car was for $1600 with 7 days left. Let's just say it went for $3200. Even an intermediate home mechanical could put maybe $5000 into it and sell it.

Then do a few sly reddit, Twitter or FB posts with people of an interest in astronomy with a picture of the car like, "Wow, I saw this great old Porsche today and it actually used to belong to Carl Sagan. And it's for sale!". Wait for it to go viral--understanding that that virality is going to be an a small niche of the internet--and wait.

And for what it's worth, have you met race fans? Jeff Gordon's minivan would certainly get above going rate on eBay. It's just a matter of much more and what the current owner paid for it.