Confused about Windows Azure Billing?
The Windows Azure Platform is based on an Operational Expenditure (OPEX) model as opposed to the on-premise Capital Expenditure (CAPEX) model that most of us are used to. This means that means that, while you pay nothing up front for using Azure storage and computational resources, you do have to understand how your use of those resources will be billed to you.
This blog post does a pretty good job of explaining how this works.
If you want to explore this subject in greater detail you can utilize the TCO/ROI Calculator that we blogged about a while back.