I'm not so sure, I had the same reaction to your comment, but then clicked through; it's a set of five thick books, essentially a history book, two textbooks, and two recipe books, at $125ea. Pricey, definitely, but phrased like that I think not so ridiculous.

Even for 5 books it comes out to $125 per book and you must get all of them.

This doesn't really qualify as pricey.

It compares more favorably with collage textbooks which you could use these as.

Niche books can justifiably command higher prices.

Depends 100% on what you're going to get out of it/them.

For five books? Have you shopped for textbooks recently (in the last 30 years)?

$625 is a goddamned bargain.