Ten years ago Maz and I flew to Australia with hand luggage and a motorcycle backpack landed at Perth and returned three months later.. Car hire and most of the way around the perimeter of Oz returning to Sydney total cost £2600 we stopped mainly in road houses and holiday parks spent two weeks in Atherton to recover and they only charged one week as it was off season still bloody hot
At that time the pound against the Oz dollar was at its lowest... The only problem was leaving Heathrow and the coach breaking down on the entry slip to the M4 (A blown turbo) and hat to wait behind the crash barrier until another coach arrived it was bloody freezing...
I will admit we do have rellies in Perth, NSW & Queensland. So that saved a bit..