Looks like you can get the source code and the eBook as a .pdf for that amount.

I think of an ebook as something I can read without internet access. Is there something like that available for free on this website?

Edit: Print to PDF works, should have realized it was a single page app ;-). Thanks!

We are giving you free access to the ebook online. If you want to take it offline, we've made a nice PDF version that you can purchase to support our ongoing efforts. If you don't want to support our ongoing efforts to make the tutorial better, you can always 'print to pdf' and take it with you offline.