Handbook of the Mathematics of the Arts and Sciences

The prices in USD are $999 and $1099, respectively.

Seems to be some special Springer "Handbook" pricing :-D, see also:

https://link.springer.com/referencework/10.1007/978-3-319-07...

Majority of academic books are purchased by university libraries. And these libraries want hardcover books. In this case, this book as 3000 pages, almost 10 books long. So, it is 100 USD for a 300 pages book.