The Economist published an interesting article looking at the value of a PhD in The disposable academic
Why doing a PhD is often a waste of time. Although a few faculty tend to complain about their jobs quite a bit I think the value of a PhD may vary between academic fields. The value may be more intrinsic rather than financial. When I entered my PhD program in management at Southern Illinois University someone at the orientation session for all new doctoral students made a statement that you are entering a profession that will lead to one of the best jobs/careers available other than that of a federal court judge. There is a substantial sacrifice involved in successfully completing the program which can take its toll on one's health and relationships. The end result is well worth it.