This study explores challenges in decision-making for product design due to insufficient cost transparency because of product variety across the value chain. Utilizing a literature review and a case study on a company, it delves into issues such as value chain consideration, product family assessment, linking effects to specific product levels, and converting measured effects. Highlighting the critical need to address these challenges for decision-making. Future research should focus on a comprehensive costing framework, explore effect interdependencies, and expand the value chain analysis.