First off, Nathan generously offers a full money back guarantee. If you don't find the book's value outweighs the cost, ask for a refund.

Second, yes, you can wade through hundreds of blog posts or whatever else to find a lot of what Nathan presents in the book. But I value my time, and the overhead of doing that filtration vs. having Nathan do it for me is worth a lot more than $200, especially if I build web apps for a living (which I do). There is relatively little new information under the sun — but I gladly pay people to package the best available information up and tie it all together nicely.