Sean Burns, Amy Lana, and John M. Budd have published "Institutional Repositories: Exploration of Costs and Value" in the latest issue of D-Lib Magazine.
Here's an excerpt:
Little is known about the costs academic libraries incur to implement and manage institutional repositories and the value these institutional repositories offer to their communities. To address this, the authors report the findings of their 29 question survey of academic libraries with institutional repositories. . . . The highlights of our findings, based on median values, suggest that institutions that mediate submissions incur less expense than institutions that allow self-archiving, institutions that offer additional services incur greater annual operating costs than those who do not, and institutions that use open source applications have lower implementation costs but comparable annual operating costs with institutions that use proprietary solutions. Furthermore, changes in budgeting, from special initiative to absorption into the regular budget, suggest a trend in sustainable support for institutional repositories.