This research examines how inter-price relationships among base and add-on products affect the sales of a new add-on product in the mobile gaming context. Based on theories of price fairness, product familiarity and price-quality relationship, a research model was drawn and tested on a sample of 6,766 weekly observations derived from 74 base games and 514 add-on virtual goods. Our empirical results show that the relative price of a new add-on product, when compared to the base game price, is negatively related to the add-on product sales, but positively related to its sales, when compared to prices of existing add-on products. Furthermore, the inter-price relationships among base and add-on gaming products are moderated by visual richness and game genre. This study provides the implications for IS research and practice.