Another vote for containers. My parents used a container to move their gear over to Perth from Vic 2 years ago as that was the cheaper option by a long shot.

As for fuel, we used to have a Commodore wagon that would get about 500km to a tank on a good run. Your car would be very similar I'd say. The price/ltr you've based it on is very reasonable too. Fuel is expensive in the Alice, hey! You probably won't need it but there's a good website which shows fuel prices around Australia - motormouth . com . au

Exciting times for you and your family!!