Blessed Book
This well-made tome is always of small size, typically no more than 12 inches tall, 8 inches wide, and 1 inch thick. All such books are durable, waterproof, bound with iron overlaid with silver, and locked.
This material is Open Game Content, and is licensed for public use under the terms of the Open Game License v1.0a.
A wizard can fill the 1,000 pages of a blessed book with spells without paying the 100 gp per page material cost. This book is never found as randomly generated treasure with spells already inscribed in it.
Moderate transmutation; CL 7th; Craft Wondrous Item, secret page; Price 12,500 gp; Weight 1 lb.