Despite a surge of empirical work on paid Massive Open Online Courses (MOOCs), a review of factors that drive the sales of them remains unexplored. The study aims to consolidate the existing fragmented knowledge by synthesizing the current literature on quality attributes, methodological approaches, theoretical foundations, and additional research opportunities for future studies on sales of MOOCs. Through an extensive literature search in Scopus and Web of Science, we evaluated 12 peer-reviewed articles across years. The results indicate that (1) most studies adopted quantitative approaches relied on online surveys or web crawling of platform databases, (2) there were three main groups of theoretical basis adopted, (3) quality attributes on courses, instructors and platforms were vital in influencing consumers' purchasing behaviors and (4) however, their weights might vary based on their platform availability and visibility. This paper contributes to spur awareness and interest in continued research towards the sales of paid online courses and serves as a reference source for higher education (HE) practitioners to improve the quality of their online courses to meet the demands of consumers.