1. A method for pricing on-line advertisement inventory, comprising: receiving a request for a price of a new product, wherein the new product includes a plurality of specified characteristics of a type of on-line advertisement display; providing a sample of new impressions that are predicted to be delivered for such new product; for each new impression, determining which bookings could be served by such new impression so as to define a set of overlapping bookings; determining the price of each new impression based on a weighted average of a plurality of prices of such each new impression's corresponding overlapping bookings; determining the price of the new product based on an average of the prices of the new impressions; and returning the price of the new product for use in a booking negotiation with a potential buyer of such new impression.