The german version of the book is not that rare.
The same seller posted for sale few copies in the past on ebay.ch, and I also saw it listed somewhere else.
In fact, I think that I bought my copy of the book (in german) from the same seller some time ago.
The price was much lower then (I think I paid around € 60).
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Speaking of the book itself, it was a major disappointment for me.
I think that there are only 20-25 pages interesting.
All the rest is just general information on the history of the swiss army knives, most like the red book from Victorinox.
Just my opinion.