If I see an old hand-made axe head for sale with or without a handle for a decent price I'll buy it because they're not making more of them.

Doing a quick search, I see multiple companies that say that they hand-make axeheads. Now, it's probably cheaper to get them secondhand, but I don't think that the supply of new ones will run dry, as a business making handmade axeheads probably doesn't see a lot of economy of scale.

https://www.lehmans.com/category/axes

We specialize in offering professionally hand-forged axes by makers who have been in the business for decades, so you find the last wood-cutting axe or wood hatchet you ever buy.

Looking at the brands they're selling:

Gränsfors Bruk, Sweden.

Snow & Nealley, Maine, US.

Hults Bruk, Sweden.

Lehmans, US. "The letter is the last initial of blacksmith who tempered the axe.", says that the axe is "Maine made", the handle is made by "an Amish family a few miles from our store", that the steel comes "from New York", but doesn't explicitly say where the blacksmith is.