We have been to Kentucky Down Under and Dinosaur World. We really enjoyed both. Don't remember the costs, but check online with their websites for coupons / specials. You can also see if they have a visitor's center for coupons. Also there is a GM Corvette plant just down the road in Bowling Green, KY. I know they have a museum / visitor's center and they may do tours of the plant. I think the tours of Mammoth Cave are pretty reasonable, but we have never done them. There is a cave tour at Kentucky Down Under that is included in the price of admission.