Xamarin is now available for free for every Visual Studio user.
This covers all editions of Visual Studio, including the free Visual Studio Community Edition, Visual Studio Professional and Visual Studio Enterprise. Xamarin Studio for OS X will be available for free as a community edition and Visual Studio Enterprise users will gain access to Xamarin’s enterprise capabilities at no additional cost.
Additionally, Xamarin runtime will be open source and is joining the .NET Foundation along with the rest of the .NET platform.
For more details, visit the Xamarin website here.