It is quite normal for larger books to be highly priced and my impression has often been that they are usually not purchased by individual readers but by libraries and are made available to read on a reference only basis.

As Turnoi's latest publications is a translation of what is considered to be a definitive book about TCM, the price doesn't surprise me and I'd consider it to be justified. I won't be buying because I don't have such an interest in TCM and I'm too much of a tight-arse to spend anything more than 100 Euros on a book, maybe would have done so on good encyclopaedias in the past, but Wikipedia suits my casual non-serious, non-academic reading requirements just fine these days.