Its been a few years since I’ve been across the top, but my experience is to expect Gove, Weipa and Horn/TI to be about the same price for diesel as you would pay in the capital cities. Cant comment on ULP – never bought any at these places. You can contact Sea Swift in Cairns for Horn and TI, and Sea Swift in Gove for Gove. Sea Swift will probably give you a good idea what Weipa will be as well.
Expect to pay about $3.00 litre for Diesel at Dog Leg Creek, and from the Shorelands Barge at Truscott. ULP will be about 10% dearer.