The Store of Requirement
Time Out says
It might not be Diagon Alley, but the Store of Requirement still has everything for the budding witch or wizard
Update 13/11/2020: The Store of Requirement has now reopened following Melbourne's lockdown.
The Store of Requirement is a wizarding shop perfect for anyone who still checks their letterbox for their Hogwarts letter (maybe it just got lost?). Their Collingwood outpost is the second Store of Requirement to land in Australia, with the first located in Samford, Queensland (about 30 minutes drive from Brisbane).
Inside the Collingwood store you'll find everything you need to live your most magical life, including a big selection of official Harry Potter merchandise. The folks here really love the "boy who lived" and take pride in stocking hard-to-get collectibles and memorabillia.
Buy your own wand, broomstick, cloak or (toy) owl and then park yourself down in the "common room" for a well-deserved glass of butterbeer. There are specific areas dedicated to each of the four Hogwarts houses, so you can rock your love for Gryffindor, Hufflepuff, Ravenclaw or Slytherin with ease.
There's also Fantastic Beasts and Where to Find Them related merch as well as plenty of games, toys, books and accessories to delight in (you can even get your own floating golden snitch). Muggles welcome.