Compilers for C# and VB.NET are always free! They come with .NET Framework re-distributable, which comes for free for anyone who has Windows installation.
I started developing with C# before I had VisualStudio.NET, using just the compiler; this is quite possible. These days, there is an Open Source IDE called SharpDevelop:
http://en.wikipedia.org/wiki/SharpDevelop[
^].
Same thing with alternative implementation of the SLR standard, Mono (
http://en.wikipedia.org/wiki/Mono_(software)[
^]) which is also free of charge. It is available for Windows, Linux and many more systems. It is ECMA/ISO standard compliant and of course, it comes with compilers. The level of compatibility with .NET is amazing. I even run my
Windows.Forms
applications (WPF for Mono is not available at this time) compiled on Windows on my Linux system without recompilation.
—SA