I have recently come back from the Flinders Ranges and found the fuel prices to be reasonable given the remoteness and (I suspect) limited sales in some of these places (e.g. Leigh Creek).
Before leaving home I used Oz Runways to plan my fuel stops. Some quick calculations soon showed there wasn't anything to be gained flying out of my way for a saving of even 10-20cents. Availability is the most important issue for me.