MHRIC Web Developer's User Group: The purpose of this group is to share relevant information geared toward school-district web developers in our four-county area. It is a forum for the discussion of general web development problems and solutions. Educational items of interest are also posted.
They list lots of alternatives and seem to give decent advice about the software. Remember that most open source software has little tech help or support so you may be on your own! But, it might definitely be worth a look.