I don't know about the UK but yes there's no quarantine to bring a dog straight into Ireland from Australia as long as you follow certain rules and get the right paperwork sorted. I'd imagine it's the exact same though.
Best thing you can do is take your dog's measurements and email a few of the animal transport companies for quotes, at least then you'll have a much better idea of the costs involved for your dog.
I see on the DAFF website they've a new requirement:
"From 1 January 2012, cats and dogs from the UK, Malta, Republic of Ireland, and Sweden will be required to have a rabies vaccination and rabies titre test prior to entry into Australia." So the cost of that test is another thing to bare in mind.
I'm not trying to run you into the ground, I completely understand your desire to bring your dog with you - I just don't think your 1,500 pound budget is realistic.