Windows Sharepoint Services (WSS) is a free download for Windows Server 2003!
Windows Sharepoint Portal Server is something more complex for larger organisations and I don't know how much it is.
There are a lot of free templates available from Microsoft tho mostly for business - one is however for classroom management.
Also there is a community of developers who publish their developed 'web parts' for free for use on sites.
I am evaluating for my school at the moment so will watch this thread for tips and tricks/pitfalls etc... and post my experiences....
hope this helps
