White Hat contains a listing of farmer''s markets - and much else
http://www.whitehat.com.au/Victoria/Markets/Farmers.asp

The White Hat Website provides comprehensive information about Melbourne and Australia in a manner that is Informed, Intelligent, Independent and (sometimes) Irreverent.. In particular, we attempt to maintain the most comprehensive online listing of what's on in Melbourne, and feedback from our users and newsletter subscribers indicates that we have the most comprehensive listing of events, festivals and markets in Melbourne.