Did our retirement trip last year- after a cruise we disembarked in Sydney where we hired a large camper van and drove along the coast to Adelaide-via Melbourne. Booked our stops along the way while still at home so we knew our route, quick trip to Alice Springs and Uluru- fabulous. Then flew to Christchurch NZ, where we hired a car for 2 weeks, again booking small homesteads/ b&b along the way
We used Freedom Australia to book campervan, flights etc so we knew basic costs- on top was fuel, food etc, used bbqs in the campsitesto cook- met lots of lovely people along the way
Probably spent about £12000 in all but we were away a long time. It was an amazing experience, we won’t be going that way again, and we are only on this earth for a short time and wanted to make the most of our time down under