Well this is how to do it Vancouver
Free admittance
but then if lets say your the Art museum and King Tut is coming, that exhibit is 15-20 bucks a person
The Zoo
free, except for Children's Zoo (although its now free I think, kids get to pet animals)
food is 5x expensive. Bottle of coke 2.50 etc
'Speciality shows' fee (but these rarely happen)
and the miniature train the kids want to go on that goes through the park, fee.
Science Centre/Planetarium
free except for parking
and if you want to see an IMAX film (they only show science IMAX films, no hollywood stuff) then its like 10 bucks. There was a controversy when I was in elementary school about whether to show Michael Jordan's IMAX film, the Science Centre was adamently opposed as it wasn't really science related. They ended up showing it because so many people wanted to see it. They did a Nascar one a few years back but that had some science related material.
Missourians who balk at 'communist Canada' would be outraged at having to pay for the Vancouver Aquarium, RoyalBC Museum, Buchart Gardens, and Science World.