Mudgereeba and Nerang have good farmers markets with some local produce.
Also the show grounds on mt tamborine has a locally grown produce shed that runs every Sunday.
Maybe look into producing 1 or 2 types of vege and using them to barter for the rest? That way you can concentrate on getting the best yields.
Organic Australian grown garlics/ginger always sell well.
Worm farms are also great, I bleddy paid $50 for 1000 worms at bunnings last week, selling/swapping those
Lil beggars could work for you