I tend to do both.
I download a lot of material to read and for some of it I purchase the book from a bookstore even after I have an electronic copy.

You are right about the cost of printing John.
It is not cheaper to print out a book than it is to buy it.
Part of the reason I download is there are some books that are just not easily available in hard copy anymore.

Another reason is that most hardcopy books would not be available in an emergency anyhow.
Most likely you would not have the book with you when SHTF or you would lose it as the S. was hitting the fan.
If you needed to be mobile then books are usually too heavy to travel.
Also I see a lot of people with the unopened text on the shelf and they assume they automatically have the knowledge available.
You need to practice skills if you are going to use them, so it is better to have an electronic copy that you have practiced the ideas in until they are natural than relying on paper.
The middle of an emergency is not the time to be learning out of a book.
With electronic text I can print off a few sheets and go out and attempt what it says.

For references it can make sense just to write (or print) copies of relevant charts, maps and tables.
(One thing I do is put simple cooking instructions with dried foods.
Like a few reliable bread recipes with the flour, a couple of slow pot recipes for the beans.)
I also have some well abused manuals and guides in my stored kits.
Since I abuse the hell out of field guides and similar texts I purchase a lot of mine from used book stores. By the time I am finished a season the texts are very marked up with editing and are starting to fall apart.

That all said I do recommend the Hesperian texts. They are simply written and good info, also very reasonably priced and the Hesperians do good things with their earnings from the sales.