Despite the well-known idea that rice is a commodity and thus it is unlikely to be differentiated, there is a large number of rice products available in the retail market, with different classification, standards, packages, brands etc. It can be observed significant variation in their prices, considering the brands, manufacturers, stores and also when the same product is considered in a short interval of time. Before these findings, we asked what the effects of rice purchasing strategies are over consumers’ expenditures. This paper proposes a mathematical model to simulate the decision process of rice purchasing by consumers with different preferences, in front of products available in supermarkets in a city of Sao Paulo state and another in Rio Grande do Sul state (Brazil).