It's a production with actors. Sometimes expensive ones. It's surely along the same continuum that explains why a 90 minute movie or season box set is more expensive than the book it's based on that takes weeks to consume. Wouldn't surprise me that consumers value it higher than "just a book."

Another way to look at it: that's 21 hours of content for $35. Doesn't seem crazy compared to, say, going to the movies or buying a $60 video game that might not even have 10 hours of gameplay.

I used to work at Amazon in the physical audiobook publishing world.

For physical audiobooks, most of the NYC publishers priced their audiobooks based on the number of CD's the book would go on. Longer books required more recording and more CD's in a box and would be priced higher. They sold, but not that well because the relative pricing was high. You could see physical audiobook sales crater once a book moved from hardcover to paperback. I did the data analytics and was able to determine the pricing formulas that audiobook publishers were using.

As Hombre said, it is paying for the voice talent and production costs. also it is a much lower volume market so the fixed costs like that are a more significant hit to the price.

Actual printing of books does not cost a lot. the materials are cheap the processes are very efficient at large volumes. That is one reason why ebooks are not always cheaper than the print versions. the print costs are small.

libro.fm audiobooks drop to $15 per book if you use their credits. It's a subscription system like Audible.

Unlike Audible, it's much easier to subscribe and quickly unsubscribe. So if you want to buy a book: (1) Subscribe for $15 to get one credit (2) Use your credit to buy a book (3) Unsubscribe.

BTW, libro.fm is DRM Free.