The price is really not unusal for library and academic reference works, I'm afraid. Books that fall under the category of "academic publishing", "university press" and the STM (science, tech, medical) market have become insanely priced over the years. My technical journals for the broadcast industry are almost always around $100 (but I can expense those!).
I've never understood if it's that way because of small print runs, or because the publishers can get away with it. I doubt it will be a big financial windfall for Stuart, at least, any bigger than with a commercial publication.