Reduction of complex product systems (CoPS) manufacturing costs are the main factors of sustainability and survival of the manufacturers. Choosing proper CoPS suppliers can dramatically reduce these costs and increases competitive capability for manufacturers. This is due to the fact that in the complex industries, the costs of raw materials for the production processes or the purchase of components includes a substantial part of the product costs. In this regard, in this paper, a tailored data envelopment analysis (DEA) model is deployed to assess and select the supplier of CoPS, helping to deduct these costs as well as eventuate in productivity of the products. In the proposed model, various suppliers of CoPS are evaluated based on a set of economic, technical, and geographic criteria. The suppliers are ranked in accordance with the obtained scores and then the best ones are chosen. Eventually, to examine the applicability and usefulness of the proposed method, a case study is conducted via which important managerial outcomes are extracted.