OCLC Research has released Lasting Impact: Sustainability of Disciplinary Repositories.
Here's an excerpt from the press release:
This report offers a quick environmental scan of the repository landscape and then focuses on disciplinary repositories—those subject-based, often researcher-initiated loci for research information.
Written by Senior Program Officer Ricky Erway, Lasting Impact: Sustainability of Disciplinary Repositories is intended to help librarians support researchers in accessing and disseminating research information. The report includes profiles of seven repositories with a focus on their varied business models. It concludes with a discussion of sustainability, including funding models, factors that contribute to a repository's success, and ways to bring in additional revenue.