A Model of consumer behavior has been formulated by using an additive utility function and the hedonic pricing approach, in a virtual market. Since, there is a time lag between ordering and purchasing products (goods and services) online and receiving them, it means the consumer makes decision under uncertainty. The level of satisfaction with products with distinctive characteristics is described by the probability vector of their expected quality. Consumer choice, as well as interpretation of the equilibrium, is derived from a mathematical process. The results show that hedonic pricing which indicates willingness to pay is affected by probabilities of the expected quality or satisfaction with product characteristics. In addition, the expected marginal rate of substitution for every two characteristics of the product equals to the ratio for probabilities of the expected quality of them.