From the announcement:
The Adventures Dark and Deep™ Players Manual is now available for sale in both hard cover and soft cover versions through the BRW Games online store.
The soft cover costs $19.95 and the hard cover costs $29.95. Each comes with a complimentary pdf version.
Adventures Dark and Deep is a RPG that attempts to answer the question, "What would the world's most popular RPG have looked like if Gary Gygax had been allowed to keep developing it past 1985?" The game is based on extensive research into his publicly-stated plans and later projects.