I read most of the comments and I have to say an entrance fee is not a good idea but I have seen malls in urban landscapes that charge for parking. Now that sounds like a way to provide for better parking services. I've seen days where you can't find good parking anywhere. Usually you can get a time credit (3 free hours) from a shop vendor provided you buy something. Valet anyone?

A fool and his money are soon parted.
-Thomas Tusser