I recently received a question asking how one avoids a "pointless mediation" when the other side makes an "obscene demand," but the court has ordered mediation.  As a form of conflict resolution, mediation can be productive even with difficult parties.  The first thing I would suggest is to look at the mediation as an opportunity to find out more about what the other side is thinking. 

In mediation you can ask why the other person thinks they are entitled to their demand. You can ask about where the number came from. Both parties can brainstorm and discuss other options for satisfying the needs of both parties.

If the other party still will not come down from their original demand, you will be free to tell the judge you tried mediation. Mediation is protected by confidentiality, so you won't have to worry about what you said in mediation being used against you in litigation.