I work the same way as Teeki. SA has a great selection of locally grown organic produce so I generally choose that.

If it comes down to the crunch though I go locally. Growing up in a fruit growing and farming area I know how important it is to keep agriculture going. I know a lot of the growers names when I see them in the shop and I will choose them over organic produce from say far north qld where there is no personal connection. (Sorry to anyone in far north qld )
That being said I pretty much 99% of the time refuse to buy fresh produce from overseas. I get so mad when I see calafornian oranges in the shop! Our poor growers are throwing them out because they don't get sales

On your question of buying organic, I quite often go to the markets where there is an organic and sustainability stall. They have a coloring system where you know the level of organic it is(ie. fully organic, minimal spray, sustainable farming). They also list the farm/grower and location so I know where and what I'm buying.