The continuous iteration and upgrading of information technology have given rise to a series of new business models, among which the C2C sharing model is particularly typical. Against this background, this paper explores the impact mechanisms of the sharing market across various sales models, where the platform assumes dual responsibilities of product sales and sharing transactions. The aim is to furnish online channel participants with theoretical insights for their decision-making processes. The results show that: 1) The rise of the sharing economy, on the one hand, enhances consumers’ motivation to purchase, generating a positive value-enhancing effect; on the other hand, it leads to a decrease in consumers’ price sensitivity, triggering a negative cannibalization effect. 2) When the C2C transaction cost is exogenous, if both the unit production cost of the product and the C2C transaction cost are low, the sharing economy will result in a loss of firms’ profits. Conversely, the sharing economy can benefit the firms. 3) When the C2C transaction cost is endogenously determined by the platform, the sharing economy will inevitably enhance firms’ profits under the wholesale model. Conversely, under the agency model, the sharing economy may negatively impact firms’ profits. 4) As the unit production cost increases, the optimal transaction cost decreases under the wholesale model. In contrast, under the agency model, the optimal transaction cost initially increases and then decreases with the rise in unit production cost. Furthermore, the agency model reshapes the impact mechanism of unit production cost on firms’ profits, potentially leading to higher profits for both the manufacturer and the platform as the unit production cost increases.