Creating a technical book is pretty hard (source: I've done it, as well as many others here). You're not just writing the book, but attempting to lead the reader from a point of little/no knowledge, so each step in your narrative needs to build completely on the last. Added to that, you're attempting to write idiomatic, clean and bug-free code to go alongside the writing.
Right now, he's clocking in at 350+ pages with his co-author. A chapter would take me a week to write, basically, so that's about three months of effort already. That's before you've done review, editing, etc., so you're looking at raw material costs of about $40-50k just to bring the text together with code in a reasonable package.
Even on the $89 package, they're adding in interview videos, interactive exercises(!), and a bunch of extra chapters. I doubt that doubles the cost, but it's probably a chunk extra (unless the book revolves around "designing software for interactive exercises", that's more code they need to write). Then on the higher package, even more chapters and videos, plus technical support (which I think is nuts).
They're pitching it as a book which probably isn't helping, but I actually think that's decent value for what they're offering. Are they going to make a profit? Hopefully, but that's going to come down to how many people are interesting in what is really a technical niche topic.
A lot of content is free; good-quality content tends not to be, and I think the world could use more like this. The market will decide, I guess.