Ok cool, congratulations to the security handbook! I have checked prices for printing books, because I am in the process of writing a regional mountain bike guide book. Although, I only find deals for 3-5$ per book... 1$ seems quite cheap to me.
It's hard to tell based on the material available on the website, but it looks like their book isn't physical. If you go through the checkout process, it doesn't gather shipping information. I assume the <$1 figure was just the Stripe transaction costs.
Yes indeed! It is an ebook. I should probably write that in the landing page :)