Come on, samth! Charging money for a book is not inappropriate. But charging (a lot of) money for a very lousy book are just pathetic. Did you ever read any of Jesse Alama's books? Thank God you didn't. That guy is tipical Racket community parasite: he parasitizes on your efforts and pains by charging his bad books, thus destroying the reputation of the entire community who turns out unable to write a fair book on how to use racket in a practical way.
And yes, the documentation is poor. I'm experienced developer and could tell that. Check this mess: https://docs.racket-lang.org/web-server/stateless.html#%28pa... WTF?