1. An apparatus for modeling costs, in association with an optimization engine and at least one merchandise store coupled to the apparatus via a network, wherein the at least one merchandise store includes at least one of a brick-and-mortar store, an online store, and a catalog store, and wherein the optimization engine is configured to receive input from the apparatus, and wherein the optimization engine is further configured to generate a preferred set of prices, the apparatus comprising: an econometric engine implemented by a computer for receiving sales data from at least one merchandise store via the network, cleansing the sales data and generating imputed variables by imputing at least one missing data point; and a financial engine implemented by the computer for receiving imputed variables from the econometric engine, receiving cost data from at least one merchandise store via the network, generating a cost model for at least one product, and outputting the cost model to the optimization engine, wherein the cost model models costs of the at least one product given the merchandise store, a demand group and a selected time period, and wherein the demand group is a group of highly substitutable products.