Production environments and systems are transforming, driven by changing economic concepts, consumer demands and ecological guidelines. Linked to this, concepts for small-scale production systems in urban areas are evolving. These systems attempt to incorporate flexibility and individuality in both processes and products in range, variety and amount, enabled by growing technical possibilities. Therefore, small scale urban production systems are affected by other framework conditions than large-scale mass producer, in particular shortened planning phases due to frequent replanning, redesign, and reconfiguration. This requires constant adaptation to changing situations and basic planning tools. As such a cost model is proposed to support decision-making in early planning phases. The functionality of the model is investigated to achieve sufficient output accuracy with a reasonable amount of input. The input contains general information about the product, the processes, and the assembly equipment and is collected exemplarily in a case study while the output suggests different options, e.g., on assembly layout arrangements, machine selection, or depth of performance.