The three different cloud costing models strategies are pay-as-you-go pricing, reserved instances, and spot instances. Pay-as-you-go pricing allows you to pay for cloud resources based on your actual usage. Reserved instances involve pre-paying for a certain amount of cloud capacity over a specified period, which can result in discounted rates. Spot instances enable you to bid for unused cloud capacity, allowing you to take advantage of lower costs, however, these instances can be terminated by the provider if the demand for resources increases. Understanding these strategies can help you optimize costs and choose the most suitable option for your specific needs.