COST 4. Have you selected the appropriate pricing model to meet your cost targets?
Use the pricing model most appropriate for your workload to minimize expense. The optimal deployment could be fully On-Demand instances, a mix of On-Demand and Reserved Instances, or you might include Spot instances, where applicable.
Best practices:
 Spot Use Spot instances for select workloads.
 Analyze Usage Regularly analyze usage and purchase Reserved Instances accordingly.
 Sell Reserved Instances As your needs change, sell Reserved Instances you no longer need on the Reserved Instances Marketplace, and purchase others.
 Automated Action Have your architecture allows you to turn off unused instances (e.g., use Auto Scaling to scale down during non-business hours).
 Consider Cost Factor costs into region selection.