The evolutionary nature of Unmanned and Autonomous systems of systems (UASoS) acquisition needs to be matched by evolutionary test capabilities yet to be developed. As part of this effort we attempt to understand the cost and risk considerations for UASoS Test and Evaluation (T&E) and propose the development of a parametric cost model to conduct trade-off analyses. This paper focuses on understanding the need for effort estimation for UASoS, the limitations of existing cost estimation models, and how our effort can be merged with the cost estimation processes. We present the prioritization of both technical and organizational cost drivers. We note that all drivers associated with time constraints, integration, complexity, understanding of architecture and requirements are rated highly, while those regarding stakeholders and team cohesion are rated as medium. We intend for our cost model approach to provide management guidance to the T&E community in estimating the effort required for UASoS T&E.