Tomorrow The Islamic Council of Victoria are having open days at many of their mosques, as they have for the last couple of years. As part of this they are also opening the Islamic Museum of Australia for free to the public. As they note, gold coin donation is welcome but not required. It's normally $12 for adults and $10 for concession.
They will have the following activities:
Guided Tours: 10am, 12pm and 3pm
Meet and Greet Bachar Houli, Richmond Football Club: 1 - 2pm
Ramadan Lecture by Ismail Davids: 11am
Kids Activity - Build Your Own Mosque: 11am - 2pm
Book Reading: Aneesa and Jamal go to Masjid: 2pm
There is also a sausage sizzle for a gold coin donation.
There is more information here about the open day and mosques that are participating in the open day.
https://www.islamicmuseum.org.au/visit/
Normal pricing listed there. $12 as stated by OP