The tomahawk ribeye (or cowboy cut ribeye) is a specialty cut ribeye steak. This ribeye
steak is extra thick – 2 or more inches prime beef with a portion of the rib bone still attached. Each steak is roughly 40 oz. Due to the required size of the meat and the bone, only 2 steaks can be cut from each side of the ribs to make a total of 4 steaks from a whole beef. – Hence the extra cost.
Winetrivia -Fun with Food and Wine 