The German edition of the book is now listed on the Verzeichnis lieferbarer Bücher (VLB), which is the German register of books in print. This means it can be ordered from any bookshop in Germany, Austria and Switzerland. The retail price is € 25 / CHF 30.80.
You can see the listing by going to www.buchhandel.de and searching for it. Buchhandel is the retail arm of MBV, the organisation which administers the VLB – there’s no equivalent in England, where the company that administers the Book database (Neilsen) is wholly separate.
Unfortunately, Buchhandel does not let me link directly to the listing, but here is the correct search phrase. Buchhandel can direct you to your nearest local bookshop from your post code (Postleitzahl).