Product line development is usually driven from a plethoria of business drivers. In order to support optimal decision making, like starting a product line project or deriving an optimal scope, we need a model that allows the integrated analysis of these business objectives. In this paper we describe an initial model of product line economics, which aims at filling exactly this gap. The model integrates characteristics of the software process with aspects of the market, where the later are used for valuation. We present the model in three layers, each adding a layer of issues that are taken into account to the previous one. This layering mirrors the levels of complexity in existing models of reuse economics.