Usability is an important quality characteristic of software (SW) products and systems. Usability costbenefit analysis models outline the potential benefits and costs of usability. These models are important for selling the usability activities for management. The implications of open source software (OSS) development context on usability cost-benefit considerations have not been addressed. Based on the insights of literature addressing the OSS development context, as well as two interpretive case studies carried in the OSS development context, the paper reveals that there are interesting parallels and differences when considering the costs and benefits of usability in OSS development context. Based on the analysis, a refined model of usability costs and benefits fitting the OSS development context is introduced. The model can be used for selling the usability activities to OSS development. Implications for theory and practice are discussed.