OER Knowledge CloudJournal ArticleMishra, SanjayaOnline learning need not be costly for learners and institutions. This reflective paper analyses four case studies from the Commonwealth of Learning to show the low cost of online learning, adopting a frugal approach and following the basic foundations of distance learning in developing courses as learner-centered, especially in the context of professional development at scale. The cost and platform data analysis for the case studies reveals that the courses adopting asynchronous learning and only learner-content interaction produce the lowest cost per enrollment and completion, with a high completion rate (66.7%). The frugal approach to course development, using available open educational resources and very low overhead costs, also contributes to the cost structures. While the content development cost differs across the four examples, the asynchronous course with a high completion rate also had the highest investments with 63.65% cost. Asynchronous online learning also resulted in a 350% return on investment. The paper presents important lessons for capacity building at scale at national and institutional levels, including for the works of international agencies promoting online learning.20252025/05/16EnglishJournal of Open, Distance, and Digital Education211-13Canadahttps://doi.org/10.25619/qy1tsg742944-0912yescost analysisdistance learningonline learninglearning platformsteacher professional developmentCommonwealth of LearningMishra_2(1).pdfCanada, North America