The current and projected costs of storage are a critical issue as organizations face an explosive growth in data. While the cost of purchasing storage hardware is readily available from vendors, there is little published literature that describes the total cost of providing storage from an operational perspective. This paper describes current estimates of both disk and tape storage based on operational experience at the San Diego Supercomputer Center which operates a large-scale storage infrastructure. These costs include not only the storage hardware costs, but also the costs of supporting servers and related infrastructure, hardware maintenance, software licenses, floor space, utilities and labor costs. A brief discussion of projected cost trends in both disk and tape is provided, as well as a comparison to current web-based commercial storage services.