Hi, I would like to study C# but I'm intimidated by Visual Studio's price tag. Any free/opensource alternatives? Thanks.
Visual Studio Express is Microsoft's free version: http://www.microsoft.com/express/windows/
Besides Visual Studio Express, I think MonoDevelop is pretty good too. It also exists for Linux and Mac. It is open-source and free - and, as the name suggest, have the Mono Project behind it so it is actively developed and will be in the future.
While I'd probably go with Visual Studio Express, as others have said, note that Sharp Develop also exists:
[SharpDevelop] is a free IDE for C#, VB.NET and Boo projects on Microsoft's .NET platform.
Also if you are a student you may be eligible for the Microsoft DreamSpark program where you can get all the professional versions of Visual Studio for free.
I like Sharp Develop's embedded Boo interpreter. I do not use it often, but when I do it is a time saver: instead of writing a small program to test some .net class (or method) I have not used often, I create an instance in the interpreter and try there.
You may also want to have a look at this Eclipse plugin for C# if you are already familiar with the Eclipse IDE.