All of my games are available to everyone for free.
However, if you enjoyed any of my games, a couple of bucks to cover website hosting costs and support my ongoing efforts would be gratefully appreciated. I think $2 per game enjoyed is a fair price. Thanks.
Dropbox (250MB Extra space)
Penzu (20% off yearly subscription)
Hole in the Wall Hosting ($10US per year for 300mb space, 30gb bandwidth)

I am using the free Visual Studio C# 2008 Express Edition IDE, and the XNA Framework is also free (Unless you want to publish XBox games, or multiplayer games that use the Live services).