Not too sure, I think at least 3 badges... which has made it a pain trying to get one into a garage without being blown up by humvees. Especially since it seems pretty rare that they arrive on the Toad. Thanks for the airport location, appreciate the help!
I remember finding two in Henry Steel Mills (I thinks that's what it's called) it was just past some shallow puddles and its quite out of the way of everything. It's a little homey shack surrounded by a small fence and it's got a sign next to it saying "Paynes house" or something and when you get close to it you can hear kids crying and dogs barking coming from inside.
That's about as much info I can give you cos I can't remember where exactly on the map it was.