If you in Sydney, Australia (in the CBD, which is downtown) your looking at $65 USD per day. Absolute rip-off.
The CBD shouldn't be for cars.
I just wish they'd build more parking near some of the suburban train stations. It's usually OK far from the CBD, but a park and ride strategy would definitely help at places 15-20 minutes out. Mascot and Green Square have both gone through a lot of development, are expecting a lot of new people, and still have tiny roads with no dedicated parking near stations.