seems like , however "Adding it all up, backpackers and regular travelers spend about the same amount on traveling annually; just over different periods of time. (dated article but the premise still holds)"
As i understand leaving Aus you will need an international vaccine certificate, a negative PCR test , a 7 day booking at an approved ASQ hotel in Phuket and the required Covid travel insurance. Prior to departure you will need to obtain another negative PCR and depending which State and when you are planning to return, maybe having to hotel or home quarantine ? Singapore Airlines are also flying To Phuket with a short Vaccine travel lane stopover in Singapore.