Discussed in stackoverflow question.
TFS 2010 basic.. same cost as VSS
Perforce - google use it? USD$800 per user
SourceGear Vault and Fortress - good VSS upscale... USD$300 / $600
SVN.. free...VisualSVN Server.. SVN 1.6.6
fi.github.com - USD$600 per user.. min 10
cobebasehq - ??
The Big Picture
On ‘Joels Test’ here are some of my favourites:
1. Do you use source control?
4. Do you have a bug database?
6. Do you have an up-to-date schedule?
7. Do you have a spec?
8. Do programmers have quiet working conditions?
9. Do you use the best tools money can buy?
source control eg Git
bug tracking eg FogBugz
continuous integration eg Cruise Control