I imported an airplane from the East Coast of the USA back in 2008, locals there weren't used to going to Australia so my guy was run around in circles certifying that the moon was made of green cheese etc. Well proven routes via the West Coast and you should be able to find ads from Australian companies which assist.
General advice on budget I've been told is convert to AUD, add GST and add $20K to get it here and get it going. We got a guy in the USA to do a pre-purchase inspection which proved worthless. Some of my friends have done well, others have ended up with projects rather than flyable airplanes.
The FAA has guidance info on the website which includes stuff specific for Australia. You do not need an Export CofA so save the expense as it requires a fairly recent annual inspection and my guy wanted to do a new W&B etc etc.