Monash, University of Melbourne, these two don't seem to rank in the top 5 of the country but I wonder how far they are from Australia's top tier schools in terms of their prestige and chances of landing a job after graduation.

Melbourne is generally seen as the country's top MBA. See https://www.best-masters.com/ranking-master-in-australia/master-mba-full-time.html and https://rankings.ft.com/rankings/2866/mba-2022