Hello there,
If I were you and if you have the money I would go with an Animal Plastics cage.
Instead of buying a mister, and waterfall put that money towards an AP cage.
I live in MN and humidity is an issue in the winter but not with my AP cages. Just use aspen and humid hides and mist here and there. They are definatley worth the extra money.
From personal expierence I wouldn't go with a water fall either. I used one for a water dragon I used to have and they can have a nasty build up of bacteria in no time.
Good luck!!
Mike