The Winix Zero 4 Stage Air Purifier provides world-leading air purification for any home environment - effectively capturing airborne pollutants and allergens including Dust, Pollen, Pet Dander, Smoke, Mould Spores, VOCs and Household Odours.
The Zero 4-Stage can be used in bedrooms up to larger open plan living spaces, featuring 4 stages of filtration; a Fine Mesh Pre-filter, Deodorization Activated Carbon Filter, Hospital Grade True HEPA Filter and Winix PlasmaWave® Technology.
Seems to be the cheapest that I could find for now, although not as cheap as before (https://www.ozbargain.com.au/node/471987)
Note that these are selling fast, at Costco crossroad yesterday there were 74, and today there were 28.
Will suggest to call them up first to check the availability before going there.