There are a multitude of people out there making prop-tomes. Bookbinders, artists, sculptors and more. I wish I was one of them. Bookbinding from scratch would be a dream project. Unfortunately, I don't have the time or skillset to do that...yet.
What I've found useful is to start off with a blank book, usually roughing it up and recovering it as necessary. That was before I found The Diary Shop on eBay. I've bought from them a number of times now, and have always been happy with their service, products and delivery time.
Handbound, their journals are a propmaker's dream - each one beautifully made and just waiting to be filled with wild imaginings and eldritch horror. Or recipes and pressed flowers, whatever floats your particular boat. In this instance, I'm making the working book of a 17th century warlock, a rather nasty individual that went by the name of Nathaniel Bane. Of him, more later. In the meantime, here's the book I'm using as a base:
The Diary Shop