If you pay $39 you get 8 fewer chapters than the actual full book. And it's online only, so no paper printing or publisher overhead. For $89 you get a video and some extra chapters (that really should be in the book you paid for in the first place). If you pay $289 (which is an absolute absurd price for any book) you get exactly what you used to get with books 10 years ago: a book with all its intended chapters, a mailing list, a glorified IRC channel and a code repo. Except, again, it's still not even a physical book (so why so expensive?).
If you pay the "Training" package ($749) you supposedly get superior in-person mentoring. Except it's not really done by the authors. It all sounds like some Tai Lopez scam.
I don't want to diminish the amount of work it took to make this book, or the quality of the authors. I'm sure it's incredible and it seems a pretty massive book. But I just don't understand these sort of things when it comes to professional programmers who write books. Supposedly they want to spread this technology they care about and want people to use it. We as programmers get paid very well, we're not in need of money. Book revenue is probably not their main source of income. So why price it out of everyone's range? You're not gonna reach nearly as many people as just selling it at a reasonable price.