I took an airboat tour a couple years ago and it was fun!
If you pay cash they give you a discount, but for three adults and one child it still cost about $100.
If you don't know already, these boats are really loud! But don't worry, they give you headphones to protect your ears. The problem with that though, is if you have a question, you have to keep it to yourself until the driver can stop to answer it.
I think this is something that everyone should try at least once in their life--while we still can enjoy it.