I think exactly the opposite is true.
Mafoo, I don't want you to take offense here, because I know you have an equisite and extremely beautiful wardrobe. But I think any good tailor would have a book like that. Now when I say good tailor, it probably comes no where near to the quality that you can afford (based on your blog and other posts re:travelling to Naples for shirts). I can bet that your stuff is made so well, most likely better than mine, but do feel that any quality guy, who does decent work would have one of these books to help his customers. The real upper eschelon guys/gals who are in the biz charge so much that it just wouldn't make sense for a newbie to go to them.
I hope I didn't come across as condescending...I love your clothes, and how you wear them, but would never be able to (in a million years) be able to affird the work that you have comissioned, and all the tailors I go to (expensive, but affordable for a city employee who saves every extra dollar to fo to once or twice a year) have said book.