Even if it's not a text book, it is still an academic work (which often cost more). For my specialty, I've seen academic-level books on pirate history that vary from $35 to the price mentioned, $115. Many new books of 150-200+ pages (in general, not just academic) these days often go for $20 or more if it's a physical book and not digital. Being hardcover will contribute to the price a little bit too. The publisher appears to be targeted towards the academic community. The subject of the book itself is a specialist topic (it's really specific). There won't be a huge demand for this book (it's definitely not one of those books you see for sale in a store). This book's print run is likely in the 300 copies range (Worldcat says 129 libraries in their system report having it). The publishers know that what audience there is for this book isn't your mainstream purchaser who thinks a book beyond $50 will always be beyond their price range. In the realm of production, in a number of cases, small runs of a product (as in, small numbers of the product itself are produced) can cost more than running products that have larger runs. This also applies to the book industry. The work put into the subject of the book doesn't exactly come easy either (I suspect the author had to do a ton of research on this less studied subject, and then the publishers likely put some work into reviewing it and making sure it was good research). It's not like a journalist just came up with it within a few months between their other jobs. While the author will probably never get anywhere near the compensation for the amount of work put into writing this book, with such a small run of books, at least at that price the author and publishers will at least get something back. With the target audience being academic and small because of the subject matter, along with the factors of publishing, I suspect all of that is why it's so high. Course, I don't work in the book industry (would love to hear their explanation, I'm just putting together what I know to try and explain it).

Honestly, this is a totally unremarkable price for a specialty academic monograph, and /u/davidAOP has the shape of the crappery on why that is. However, as there are so many copies in Worldcat, this is something you should try to get from your library through Inter Library Loan. Even your public library can get a book like this for you, although they may have to pass the ILL fee on to you. Basically your librarian emails a library who owns this and asks to borrow it, the owning library says "no prob" and mails it out with an invoice for $20-25, the library pays that invoice, and you get the book for 1-3 weeks. This is very normal and happens all the time, it happens so often that libraries get a special super-low rate from USPS to mail books around the country. So don't pay that $115 just yet!