Free: Contests & Raffles.
If you have a hunting dog, or can go with someone who does then my vote is pheasant release sites. Just wait till 10am or later when crowds have thinned out so you don't have to worry as much about some jackwad shooting you and/or your kids. You may get a shot at some pheasant, and if lucky might get to do some pass shooting at ducks or geese if they fly by low enough. Course thats the only bird hunting I have done and am hooked now, so I am probably biased.