To get it into context, first is a map of Australia; About the same size as continental United States but with lots more deserts.
Finally, a close up of my local zone of 160km of my house in Melton West.
So you can see that there is a fair bit of land as well as some of Bass Strait in the zone, and a fair bit of that land is good farming land. A lot of Melbourne's fresh food comes from within the zone as it is the second largest urban sprawl in Australia. Luckily we have a green belt (or a brown one if you really look at it) of about 15km between us and the urban boundary. This is fortunate, because that is where the olive grove is that I will be getting my olives and oil from when I run out of stockpile!
Now that I have put it into context myself, it really doesn't look that hard. Just a bit more research of local suppliers and bob's your uncle. I have potatoes, cherries, nectarines, peaches, flour, olives to name a few that I have discovered so far. I am going to start to update my account at http://www.localfoodmap.net/ with the things I have found so far over the next few days. This will help others in my area reap the rewards of my challenge. Thanks to Rosemary who runs the site for suggesting it in one of my many reader comments