Producers would estimate the products price within range values rather than an exact price. They tend to ask consumers “how much money do you want to buy for a product?”. Since this question relate to price and the intensity of purchasing, the study on this cases should establish a set of questionnaire carefully in order to avoid misleading information (Monroe, 1973). Then these set of question answered according to quality of commodities rather than market demand. Westendorp (2003) propose four questions of price sensitivity measurement (PSM) that improved continuously by following researchers. Though the results should not be applied in tariff determination directly, but it can be used to estimate the range of suitable and optimal price.