A co-op is a great way to buy bulk, often organic/bio dynamic produce and a discounted price. It isn't quite wholesale but still a lot cheaper than the stores. It also reduces food miles and packaging.
It is also a great way to get to know like minded families and enlarge your community.
Here are a few links with info on co-ops and their locations:
Friends of the Earth
Organic Food Directory
Source Wholefoods - Hobart
Starting a Co-op