System, method and computer program product for estimating the cost of a product and/or service. The product and/or service comprises a multiplicity of components. One or more first components with no cost dependencies are determined and assigned to a first tier. One or more second components whose costs depend on the costs of the one or more first components are determined and assigned to a second tier. One or more third components whose costs depend on the one or more second components are determined and assigned to a third tier. A determination is made if any of the one or more third components were assigned to said second tier, and if so, such one or more third components are removed from the second tier. One or more fourth components whose costs depend on the one or more third components are determined and assigned to a fourth tier. A determination is made if any of the one or more fourth components were assigned to the third tier, and if so, such one or more fourth components are removed from the third tier. A determination is made if one or more of the fourth components were assigned to said second tier, and if so, such one or more fourth components are removed from the second tier. An order to calculate costs of the components is based on the tier to which they are assigned, the lower the tier the earlier in the order.