Genetic Algorithms (GAs) have been identified as an innovative and useful approach for dampening the Bullwhip Effect along supply chains. This paper extends previous work by developing an improved supply chain model that incorporates additional cost factors such as ordering cost, item cost, distribution cost and production cost. The revised model is then used to examine one element of the Bullwhip Effect, i.e. price fluctuation strategies. A GA is employed to determine the ordering policy for each member in the model that minimises cost. The research illustrates how the GA performs if a sales promotion is introduced. From the experimental results, it is shown that a GA can help determine an improved ordering policy and reduce the total cost across the supply chain.