I remember looking at a 1963 Porsche 356 Coupe (1600 Normal) in 1984 that was in average, unrestored shape (needed a headliner, seats and paint) that had an asking price of $3,600 ... and remember thinking ooo"...this guy is nuts if he thinks he's ever going to sell this 21 year old car for more than it sold for when it was new!"ooo .... then, when I went back to make him an offer about a week later, I learned that he sold it for his asking price just two days after I looked at it. Now, that same car, in the same condition it was in 30 years ago .... would sell for ten times his asking price!
I bought my first 356 (a Pre-A Speedster) for $350.00 in 1965 (it was 12 years old at the time) .... today, the same car would sell for about $200,000.00 at auction. Then in 1967, I bought a 1959 356 Sunroof Coupe (1600 Super) for $750.00 ... it had about 70,000 miles on it and had just gone through a complete engine rebuild. Today, the same car would sell at auction for between $75,000.00 - $95,000.00.
Now I own two rust free 1992 Sentra SE-R's. Both are 100% stock and both have sunroofs. The interiors are almost perfect and they both run like new. One has 153,000 miles and the other has 220,000 miles on it .... and I'm keeping both of them until someone offers me $500,000.00 .... EACH!