考慮一個同時生產高價與低價產品的廠商，為了提升高價產品的銷售量，推出買高價產品免費加送低價產品促銷策略，以創造高價產品的買氣。本文以高低價產品保留價值不同建立代表性消費者的效用函數，來分析廠商推出買高價產品免費加送低價產品的促銷方案是否能打動消費者，並創造自己的利潤。研究發現，買高價產品免費加送低價產品的促銷策略會使原來偏好高價產品的消費者全部選擇促銷策略，因此不再有人單買高價產品，而部份低價單品消費者也會選擇購買促銷策略的產品。當高低價產品的保留價值差異愈大時，偏好低價產品的消費者移轉到促銷策略的數量愈少，促銷策略對廠商愈不利，而當高低價產品的保留價值差異愈小時，偏好低價產品的消費者愈易移轉到促銷策略，因此促銷策略對廠商愈有利。

Our analysis considers a firm will adopt a strategy to sell the bundle of both high price products and low price products to promote it sales and profits. We build a representative consumer’s function with different reserve value to analyze the quantities affected by the promotion strategy. The research result shows that the strategy to sell the bundle of both high price products and low price products will transfer all the consumers buying the high price products to the promotion strategy. It’s not beneficial for the firm to adopt the promotion strategy when the reserve value of the high price products is high and vice versa.