I have had a PR firm recommended to me that costs $500 a month (three month minimum). Of course, they are quite sure that their connections can get me not only many radio talk shows, but even national TV exposure. But I was somewhat surprised that they admitted that they found it hard to believe that the book hasn't already received national attention, in light of recent disasters.
I think I am going to go forward on it. If their work gets me 500 extra book sales a month, it pays for itself. And the exposure of the general public to the scale of the problem is worth a bit to me even if it doesn't pay off in book sales.