Willingness To Pay (WTP) of customers plays an anchoring role in pricing. This paper proposes a new choice model based on WTP, incorporating sequential decision making, where the products with positive utility of purchase are considered in the order of customer preference. We compare WTP-choice model with the commonly used (multinomial) Logit model with respect to the underlying choice process, information requirement, independence of irrelevant alternatives. Using WTP-choice model, we compare equilibrium prices, demands and profits of several contexts: without considering inventory and with stockouts - lost sales and backorders for favoring customers and for availability favoring customers. One of the interesting results with WTP-choice model is the loose of retailers; prices are not coupled but profits are. That is, each retailer should charge the monopoly price as the collection of these prices constitute an equilibrium but each retailer's profit depends on other retailers' prices. Loose coupling fails with dependence of WTPs, dependence of preference on prices or batch pricing for heterogeneous customers. We show that competition among retailers with dependent WTPs can cause price cycles under some conditions. We consider real-life data on sales of yogurt, ketchup, candy melt, and tuna, and check if a version of WTP-choice model (with uniform, triangle or shifted exponential WTP distribution), standard or mixed Logit model fits better and predicts the sales better. These empirical tests establish that WTP-choice model compares well and should be considered as a legitimate alternative to Logit models for studying competitive pricing for products with low price and high frequency of purchase.