Here is a group that just created a pandemic announcement. (radio)
It is not clear if it is a Public Service Announcement. I do see from their discussion that they paid $500 for 1,400 airs.

They are testing to see if it attracts more people to their web site.

Panflu prep radio ad:
Note: The first time through the sound might break up. After it runs through the first time, just re-hit the "play" button and it should work fine the second time.

Web site:
I just wanted to let everybody know about our latest project and to see if anyonehas any additionalideas....