What a great topic. Why don't 'they' make $500 heirloom guns? Because people will pay way over $1000 for one. 99% of us who buy guns want accurate tools to use, yes, like Henry Ford's production line. The same reason I drive a diesel pickup. It is a tool, not an exotic sports car, and priced that way. I don't want a fancy walnut stock or a polished deep blue finish that I have to worry about when taking it in the field. Plastic and brushed stainless work for me.
If I want an heirloom gun I will go to a maker and select stock material and have them fit it to an action and barrel of my choosing. Meanwhile I will keep my father-in-law's M1 Garand, my grandfather's 1911 (not 1911A1), and my father's Python where they won't get damaged. Yes, they get fired all the time, but, not out in the woods. And they will be handed down to the next generation who will care for them the same. Hunting guns? Nope.
Having said that, my last purchase was a nice Lyman Great Plains Hunter muzzle loader. Beautiful stock and metal. No, not polished, it is still a field gun
I am happy as a pig in s*** that we can get these inexpensive rifles that shoot so well. I will probably buy another one in the near future.
PS and you can always take one of these inexpensive shooters, get a nice stock made for it, have a gunsmith polish and blue it to your satisfaction, maybe even add some engraving and nice checkering. Then you'll have your heirloom gun. And, yes, the stock maker will probably use CNC machinery to inlet and shape the stock, maybe even do the checkering/carving. Same with the metalwork, except the polishing and bluing part. So, you'll come away with a nice gun for around $1000 that used to cost several thousand.