What you save with "free" software you lose in development time and effort!
First, not necessarily, and second, you lose in retraining and rewriting. In this case the cost of licenses plus retraining (for JR) would probably exceed the cost of adding some desired functionality using the open source tools he's familiar with, or simply downloading and modifying an existing open source application.
Microsoft likes to use costs of migrating from Microsoft when doing Linux TCO studies, but street does go both ways.
BTW, I say this as a .NET developer.
I am not saying there are not cases where a closed source solution will be cheaper but its sure as hell ain't the case they are typically any easier..