I just did a quick write up on the latest National Park we went to
Cape le Grand in Western Australia the fees are included in the post.
Worth noting too that when you get truely remote you are in general allowed to camp for free so long as you don't camp near homesteads or stock watering places or Native land. In Western Australia up north they have 24 hour stoppings on the main highways - which is as the name suggests - free, just a loo but OK for the price!