Hi!
My gf and I just finished a 1 year working holiday in Australia.
If you're from the UK, you'll find Australia pretty cheap, except in the big cities.
I'd strongly advise you against travelling by bus. It's really expensive, and doesn't really give you any freedom. I'd get a cheap car, unless you plan on living in cities for long periods of time. In the end a car and a tent (or a car you can sleep in) will make you save a lot of money and give you real autonomy. Are you travelling alone? You can put ads in hostels to get a travel buddy and share costs. Some friends of ours bought a AU$1000 commodore, and drove it all around the country. Just make sure it's mechanically sound, and has a roadworthy certificate, although repairs are also pretty cheap. If it needs an expensive repair, just give it to the local mechanic for scraps, and get a new one. Really. We wanted a 4WD so we got a great Pajero we could sleep in, with a trailer to carry all our stuff but that's because we had a lot of diving gear. Most backpacker couples have enough with a Commodore or Falcon station wagon.
Best places to buy cars are, depending on your budget, those free or cheap 100% classifieds magazines, the backpackers carmarket (but beware of wrecks), ads in hostels and the most expensive option: used car dealers.
About your budget, I'd say you can get a dorm bed for $20 to $40 depending on the place or city. Again, a car with the $50 Camps book will save you heaps. National parks are usually free or pretty cheap ($5 per night/person) with some exceptions (Fraser Island comes to mind)
We worked for three months in a hotel in the Kimberley, and made enough money so we didn't have to worry about money again (and we were diving and eating very well). Ask me by PM if you're interested. Based on other people's opinions I'd advise you against doing fruit picking.
Also in case you need it, register on couchsurfing.org
Oh, and if your Mac Pro is homeless I can host it while you're away... Does it come with a monitor?
You'll love it.
Cheers
