$79.99? Is this an error? Player Core 2 is the same length for $59.99.
The 4 Core books are heavily discounted to be less of a barrier of entry.
From the blog announcing the most recent price structure:
Paizo Pricing & Sustainability Update Blog wrote:
Holding the Line on the Core
Contrary to what I’ve outlined above, we’ll keep the price of the hardcover Core books (Player Core, GM Core, Monster Core, and Player Core 2) at $59.99 through at least the first printing. We feel these books are essential first purchases for Pathfinder players and want to hold the line on price increases as long as possible to reduce the barrier of entry for new players.