It will be good experience one way or the other.

That said:

1. They aren't paying you enough.
2. The kind of folks that come to those type of events generally aren't the kind of clients you want for private sessions. Of course, there are exceptions, but those who want to spend $10 on a photo are usually not likely to spend $1000 on photos later.

Sorry for the short reply, but I'm in GA right now with limited access.