Abstract: Disclosed is a system to price usage of a user-action Probability estimation system provided by an advertising exchange system. A bid from each bidder in an auction for an advertising opportunity is presented in a computer. The bidders comprise a first group of bidders that utilize the Probability estimation system and a second group of bidders that do not utilize the Probability estimation system. The bids are processed by determining a first equilibrium bid for a first bidder as a member of the first group. The bids are further processed by determining a second equilibrium bid for the first bidder as a member of the second group. The system then utilizes the first equilibrium bid and the second equilibrium bid to determine a value of utilizing the Probability estimation system.