Check out my Pinterest pages. I have lots there and so do most people. There is the one main one and I have just added one called something like New Spellbook. I really need to organize it and do some clean up. I am printing out all the various BOS ones. I have over 100 so far.
I also make spell books from the bought décor books that I find in GW and thrift stores. Like this:
These are perfect to print out pages and Mod Podge.
Here is one I did back a few months ago for the Winter Reaper:
This is the simplest way. You can also take old books and make your own book and add the pages already printed out or do the lettering yourself.