Free build servers for .NET [closed]
You may want to check out AppHarbor - when you deploy your latest changes using git or Mercurial, your application is built automatically and any unit tests you have in the solution are run. The application is deployed if the build and your unit tests succeed.
They also have a dashboard to view / deploy any of your 10 most recent builds.
Also: They have a free plan.
Another idea: do you really need your build server on the internet?
How about putting only your code repository on the internet (Github, Bitbucket, Google Code...)?
One of your project members could set up the build server at home. As long as it's online 24/7, it can pull the repository from the internet, make the build locally and upload the results via FTP to some webspace where you all can access it.
Of course that's not as comfortable as a "real" internet based solution, but cheap.
Hudson is an continous integration build server. It´s written in java, but it is also compiles and builds .NET projects. As far as i know is it open source.