As Millsy stated, you can try Aikikai (http://aikido.org.au
They have dojos all around Melbourne and the main dojo is located near the City with easy access via public transport. There are multiple classes every day.
Yamada Shihan is the Patron of Aikikai Australia since Sugano Shihans passing and he will be the Guest instructor at the National training week in January.
All the instructors are students of Sugano Shihan (http://aikidomelbourne.org.au/pages/...nstructors.asp
As has been stated here on multiple occasions, go and try a number of dojos to see which is best for you.