Just my $0.02, I don't know the guy selling the item so I won't speak to his character or motive, and that really doesn't matter, but I see that price, and as a young guy with a wife and kid, I say holy crap! My Uncle, on the other hand, who used to own a Super Bird he restored himself and is now restoring a 70 convertible Challenger almost exclusively buys only NOS parts, but that's what he wants and he can afford to do that, and is not stupid for doing that, he just has the money.
My mom said, when I started collecting baseball cards years ago, something is only worth what someone is willing to pay for it. If you have the money and want it, buy it. If you don't have that type of money, like me, then don't buy it. It's pretty simple.
Most of these parts are not being remade and in NOS quality are extremely rare. The sellers know that and determine what they would like for it and list it. If someone has the money and buys it, then good for them for selling it at that price. If it doesn't sell then they may adjust the price or may decide not to sell it. Basic economics.
If you are like me and can't drop thousands on NOS parts, do like I do and look around and find the best quality part for the money you have. I personally like to find the deals that someone is selling cheap, but is in good condition and just needs to be polished or repainted, buy those at what I feel is a good price for MY budget, and then restore them.
I am not mad at those people that can buy NOS, I am happy for them, and love to see their cars. I also like to see the cars from the guys like me that don't have unlimited funds and put sweat equity into them. They are all Mopars after all.