Hopefully, by now everyone is aware that you can try out Mobile Services in Windows Azure free for one month. Past the first month, you can keep your mobile service in free mode (with a free 20MB database for 12 months) while you develop and test your app. With all of this free trial goodness, some folks have been nonplused to find that the Windows Store and Windows Phone quickstart tutorials for the new .NET backend require Visual Studio 2013 Professional (a non-free edition).
This requirement is really due to the way that the quickstart download is packaged for Windows Store and Windows Phone apps. For convenience on these .NET platforms, the client and service projects are both included in the same solution. This creates a problem for Express editions because you cannot open such a solution in these free editions of Visual Studio--hence the "requirement" to use Professional.
Here are some options for trying out the Mobile Services .NET backend tutorials without having to buy Visual Studio Professional 2013:
Hope that helps,
this is a real pain when using the free versions of visual studio. If MS are serious about getting these tools out there then sort out the utter stupidity of 3 different versions of VS express its confusing and pointless and makes implementing the new features such as this a complete pain. VS 2013 pro is currently £1200 per year in UK ridiculous!