Price check Please?

Hey all, new to these forums, Just wondering what an account with the following would be worth,

Thanks.

Garrys Mod
Mount and Blade(Full Version)
Call of Duty Modern Warfare 2
Left 4 Dead
Left 4 Dead 2
Team Fortress 2
Portal
Counter-Strike Source
Half Life 2
Half Life 2 Episode One
Half Life 2 Episode Two
Half Life 2 Lost Coast