Cost Estimating Methods. Cost estimating is a valuable tool that is used in each of the acquisition phases. There are a number of cost estimating techniques that can be used in estimating the costs of a future and current weapon system. few of the most common cost estimating techniques are listed in the Defense Acquisition Guidebook (DAG) and are: 1  Parametric: The parametric technique uses regression or other statistical methods to develop Cost Estimating Relationships (CERs).