I'm a .NET developer and want to write an IOS & Android app in C#. I've had a read around Xamarin for Visual Studio which looks interesting if not a tad expensive!
Do you need a Mac to debug your code? Do you just need a networked Mac to actually deploy the app to the Store?
Is the best option just to buy a Mac and run Windows with VS in a VM or can I just use my windows machine, write & debug the code in Windows then just hook up to a networked Mac for final deployment?
Yes, you must have a Mac to do Xamarin.iOS development. The Mac is required for building as well as running the iOS simulator. You can either use it as a build server, and actually do your development in Visual Studio (either in a standalone PC, or on a VM running on your Mac), or you can do your development directly on the Mac using Xamarin Studio as your IDE.