To show how costs of preserving digital research data can be estimated, this presentation uses the case of the Data Archiving and Networked Services (DANS) institute, a well-known trusted repository. The approach used is the activity based costing (ABC). The DANS-ABC model has been tested on empirical cost data and results are presented. The economic value/benefits analysis of research and data infrastructure investments is based on the recent benefits studies conducted by Charles Beagrie Ltd. Approaches that estimate minimum values and approaches that measure the wider value are analysed. Both the cost and the benefit analyses provide funders, managers and other decision-making stakeholders with valuable information connected to the strategic goals of an organisation.