Eliminating cat oder... any advice?

I'm a new cat owner, and have never had any pets other than goldfish before. My dad is very concerned about the smells that the cat will bring to our house, and I'm looking for advice on that. I've heard about those automatic litter boxes, but the ones that won't kill your cat are wayyyy to expensive... I think those might be a last case cenerio. We're planning on buying an air purifier to go near where the cat does it's busnuiss, and we are going to clean the box regularly. Other then that, any advice on eliminating cat oders?