exorbitant - eks-OR-bih-tent - unreasonably high, excessive, unwarranted, disproportionate

Example: "The NY Times suggests that one of the possible reasons for a delay in the Nashville Tea Party next month is the exorbitant cost of Sarah Palin's reported speaking fee of $100,000 - yet to be confirmed, but if true it places her not that far off Tony Blair in the world list of unbelievably-overpaid-speakers."