A question that I get quite frequently from developers looking into the Windows Azure platform is “What will my application cost me?”.
The response to this actually consists of two parts:
The first part is only loosely coupled with Windows Azure and relates more to understanding the computing complexity of an envisioned solution. And it is actually the hard part, with the second one revolving mostly around adjusting sliders on this page http://www.microsoft.com/windowsazure/pricing-calculator/ and checking out the results.
To assist in “guesstimating” the resourcing for an application, Tony Bailey has recently released a great set of four sample assessments in his blog entry here: http://blogs.technet.com/b/webtech/archive/2011/09/15/plug-in-your-numbers-for-windows-azure-pricing.aspx
I would recommend anyone getting started on Windows Azure to take a look!
One minor thing to keep in mind for applications with time-variable resource requirements (meaning: your application will be auto-scaling and consuming more or less resources, depending on the time of day, day of month, …): Feed the pricing calculator with your AVERAGE resource requirement. Windows Azure uses a pay-as-you-go model, so you will not be paying for your maximum resource usage, but rather for what you actually consumed.