Rails scalabilty

see this excerpt from the rails tutorial by Michael Hartl on rails scalability.

"Before moving on with the rest of the introduction, I’d like to take a moment to address the one issue that dogged the Rails framework the most in its early days: the supposed inability of Rails to “scale”—i.e., to handle large amounts of traffic. Part of this issue relied on a misconception; you scale a site, not a framework, and Rails, as awesome as it is, is only a framework. So the real question should have been, “Can a site built with Rails scale?” In any case, the question has now been definitively answered in the affirmative: some of the most heavily trafficked sites in the world use Rails. Actually doing the scaling is beyond the scope of just Rails, but rest assured that if your application ever needs to handle the load of Hulu or the Yellow Pages, Rails won’t stop you from taking over the world."

Just curious, why isnt heroku a viable business solution?

Is that whole book available online?

Heroku is just way to expensive it seems. I may be wrong(Due to not understanding dynos) but when you play with their pricing scale it becomes very expensive for what seems to be very little processing power.