Knowledge sharing behavior in virtual communities has long been an important area of research. Prior related research has primarily focused on relational virtual community (RVC) where knowledge sharing is regarded as a social exchange behavior, heavily depending on the social concerns such as reciprocity, identification and norms. The objective of our study is to investigate knowledge contributors’ satisfaction in a distinct type of virtual communities (transactional virtual communities, TVCs), where knowledge sharing is mainly guided under the principle of economic exchange, and cost-benefit tradeoff is the primary motives for knowledge sharing. Drawing upon the goal attainment theory, we examine the effects of two types of benefits (e.g., extrinsic and intrinsic benefit) and two types of costs (e.g., actual and opportunity cost) on knowledge contributors’ satisfaction, as well as the mediating role of perceived net goal attainment. A field survey with 205 subjects in a specific TVC in China was conducted to test the research model. We find that knowledge contributors’ perceptions of extrinsic and intrinsic benefits and opportunity cost significantly influence their satisfaction through the full mediation of perceived net goal attainment. Implications and future research are discussed.