... just a note to outraged parents: this is not a children's book, it is a *parody* of children's book. It should not be read to children, but it is not *intended* to be read to children.
No doubt some book sellers, dealing with many books every day and misled by the cover (which covers up the f-word), put this book in the children's section. But I've seen book stores with Flaubert's "Sentimental Education" in education book, or Pirsing's "Zen and the Art of Motorcycle Maintenance" in the "automotive maintenance" section. That is not the author's fault.
The book itself is quite amusing, although, like most children's books, which it copies, quite short. As for the price, quite apart from supply and demand, like with "real" children's books, you are not, really, paying for the text -- it is too short for that (as most children's books are) -- but for the artwork and the production value, which are both very good.
Whether it is worth the price is a personal issue. Some people will be greatly amused and would enjoy it as a conversation piece. Some people will think it's very overpriced. But I am just noting that much of the criticism of this book in the reviews (that is corrupts children, that it is overpriced because it is short, etc.) is just not to the point.