I often head down to the Sunday markets at the drive in on a Sunday morning.
It varies from week to week what you will find, in the flea market section. It is also a better way to do a sale if you don't have the room for a garage sale at home.
The fruit and veg area always holds bargains better that the super market.
At $1.50 entry as a buyer [kids free] it is an inexpensive price to amble around looking at all the wares

An excellent sunday market full of the cheapest and freshest fruit and veggies in Adelaide. They also sell first and second hand items. Entry is $1.50 per adult and free for children under 16 years of age.

Approximate cost: $1.50

a great sunday market full of fresh veggies the cheapest i have seen in adelaide, always very busy this market especially to park, they also sell other items like nic nacs, etc market opens 7am cost $1.50 per person lots of interesting things here for sale, best to get there as early as possible otherwise all the good things have sold