I would be up for a special edition leather core book with sewn in books marks and the like.
Sewn-in bookmarks can be nice, but I've found that the ribbons sold for books are the same ones sold in spools at craft stores, and in a Martha Stewart moment a few years ago, I bought a pile of assorted color spools on clearance. It's been easy since to glue in ribbons of the appropriate color to any game book I need them for, and it's a good way to distinguish which book is yours at the gaming table too. Best is a few different colors coordinating with the product so you can remember which color ribbon you used to mark which page.