These people are trying to solve this problem. They have also taken a very interesting route and built a robotic mannequin which can change it's shape.
In any case I don't think I will ever be able to give a better overview than the site itself.
The first thing with these kind of fruit picking jobs is they are pretty seasonal and differ quite a bit from state to state.
I spent 9 months in OZ, most of the time in northern Queensland working at a lime/lychee farm and some time at a banana farm. Since you are not in OZ yet, I doubt you will have any luck with gumtree/craigslist. Even if you are there it's pretty hard to get the job that way - the farmers really like to make sure you WANT to work and can physically do the work (at least I didn't manage to find work via gumtree).
The thing you have to do is go to the farms directly and talk to the owners/recruiters face-to-face. We bought a cheap 2500$ car between 3 people from Sydney and started driving north along the coast. There's quite a bit of work in the tropical areas during the summer months - bananas, mangoes, limes, lychees, avocados in late summer etc.
So my advice would be - get a cheap car, travel and work at the same time! (some farms hire only for the harvest period which for some produce isn't very long!)
I guess it's one of the virtues of having a population a tad smaller than 1.5 million.
[1]http://en.wikipedia.org/wiki/Estonian_ID_card