Broadly speaking, there are two major approaches to creating a price model for IT. There is the Utility-based model, in which pricing derived from actual consumption of CPU cycles, RAM, bandwidth, storage, etc. In this model, if you stood up a virtual machine for one week you would only pay for the actual amount CPU cycles and storage you consumed.
Alternately, there is Service-based pricing, which advocates a fixed price based on either the service itself or some other unit of measure such as hours, etc. In this model, if you stood up a virtual machine for one week you would pay for how many hours the VM was active, whether you used it or not.
I always council my customers to adopt service-based pricing. I think utility-based pricing is the wrong approach for IT departments, especially infrastructure teams. Here are my reasons: