Always looking for new, exciting, artsy, and moreover cheap things to do within the city of Melbourne, the Flinders Lane Gallery walk seemed to be a great idea. Easily accessible through various and numerous public transport methods, the lane is covered in amazing examples of Australian and International street artists. These works are of course free to view and sometimes more interesting and thought provoking than anything you could see in a gallery.
Yet there are over a dozen galleries housed within the lane including fortyfivedownstairs, mailbox 141, and the Robert Lindsay gallery. If you look hard enough you'll be able to find a gallery around every ten metres, however I recommend taking either a copy of the art guide or the art almanac with you as some of the galleries are pretty hidden and tricky to find.
Best of all, the majority of the galleries are free to enter and browse so you're pretty much set for a cheap day out.