Based on 30 interviews with instructors who implemented affordable materials in their courses at a large research university, this study explored their motivations for using such resources, the processes they employed, and the extent to which the new course materials influenced teaching methods and perceived learning outcomes. Results suggest that most instructors were motivated by both student cost savings and hoped-for improvements in teaching and learning. Instructors' choices--such as the decision to adopt an existing textbook in full or to curate a collection of disparate materials--were strongly influenced by their perception of how well available resources aligned with their own teaching and learning goals. In general, instructors felt student learning slightly improved after they put the materials into use, but the extent of improvement seemed to vary across the approaches to implementation. Librarians can leverage these results to help motivate and support the selection and implementation of affordable materials.