Best time to buy Yank tanks with the good exchange rate! (1AUD = 0.94USD)
Make sure you only buy cars from the West Coast! Only for the fact that a majority of cars wont be rust buckets as opposed to buying from east.
If you buy any car, you choose a reputable shipping company (i use Emo-Trans
http://www.emotrans.com/ ) to take care of taxes, customs duties etc you would have it then packed into a container in LA then have it shipped to Freo.
So roughly a good example of a '69 'stang around 25k USD = 30,000AUD
You will only pay GST on the purchase price, container and any associated fees be sure to budget circa 8-10k AUD
If you do find the car you like and paid a deposit etc.. best to get an Import Approval from Customs before you start anything further. Here is a link to the PDF:
http://www.infrastructure.gov.au/roa...VSB10_Form.pdf
With the later model cars, its a bit waste of money especially when you are within the 15 year rule so any car after 1989 has to be converted = extra cost.. Best to stick with '60s cars and you're laughing.. its not hard to drive LHD at all.