You still need to ship it inside the US to the boat dock, and then pay to put it on a boat, and then pay to ship it from the australian dock to the homeowner.
Freight costs are so cheap they're essentially negligible. There's a reason why it's cost-effective to make stuff in China, and ship it all the way across the Pacific to the US, instead of just making them in the US.
Yes, so the only extra part is the boat in the middle. Boats are cheap. (OK, Australian unloading costs are crazy from what I've heard, because of the unions here..)
Put it on a boat. Shouldn't cost more than shipping inside the US.