Okay, but the car you sold for $500.00 forty five years ago isn't around to offer today and it wasn't a CA black plate car with but 57K and what looks like fairly expensive fresh paint in a period correct color albeit using an incorrect paint system.
Your car also probably had rust as well as all the minor damage that daily driver use brings while this car has neither.
I'm also quite certain that the offering price is negotiable, like I have 18K cash right now and what can you do for me?
If one had a burning desire to own a really nice driver VW of this period, this car might well be a good buy for 20K.
You'd of course have to bone up on what to look for, easy these days online and you'd have to inspect the car personally before writing the check.
Still, most of these cars ended up as the first cars of high school students in the seventies and then maybe as their college cars and then later showed up in either a yard or a low-end used car lot.
Aren't many decent mostly original cars left and there's no way you'd be able to bring a rusty parts missing valve having already been swallowed car to the condition of the one offered for even the 24K asking on this one.