Paying can get you nice to nice places, to see/hear/watch/ponder nice things…but so can not paying!
Events pages that have stuff that is usually free/cheap in Melbourne:
White Hat (General Listings): http://www.whitehat.com.au/Melbourne/Events/Calendar.asp
Loophole Community Centre (Thornbury): http://loopholecommunitycentre.org/event
Melbourne Uni (incl. VCA): http://melbourneuniv-web.ungerboeck.com/coe/coe_p1_all.aspx?sessionid=ejpff3fdnfdnfdkfek
Monash Uni: http://www.monash.edu.au/events/index.html
Art Gallery Openings: http://www.melbourneartopenings.blogspot.com/
La Trobe Uni: https://www.latrobe.edu.au/events/eventSearch.jsp
RMIT: http://www.whatson.rmit.edu.au/
City of Moreland: http://www.moreland.vic.gov.au/about-council/news-media/events-calendar/home_events.html
Fed Square: http://www.fedsquare.com/index.cfm?pageID=16
Wheeler Centre (Lunchbox/Soapbox & Debut Mon FREE): http://www.whitehat.com.au/Melbourne/Events/Calendar.asp
City of Yarra: http://www.yarracity.vic.gov.au/Services/Arts%20%26%20Culture/Festivals%20and%20events_2010.asp
City of Melbourne: http://thatsmelbourne.com.au/WhatsOn/Pages/Whatson.aspx
National Gallery Victoria (NGV): http://www.ngv.vic.gov.au/whatson/pub/events
Australian National Academy of Music (ANAM): http://www.anam.com.au/cms-whats-on/calendar.phps
Maths Assoc of Vic: http://www.mav.vic.edu.au/public-lectures/2010/index.html
State Library of Victoria (SLV): http://www.slv.vic.gov.au/programs/whats_on/index.html