Imagine I have a car in Thailand and I want to get Australia, is there any ferry that cross from Asia to Australia? How much is it? No problem if have to drive to another country or if there is no direct ferry and must take a combination of transports.
I can't help with the logistics of actually getting the vehicle between Thailand and Australia, however despite what is and isn't possible there, there's no cheap way to do what you're asking.
Australia has a relatively strict process for approving imported vehicles, which would normally only be worthwhile if the car was in some way special. If the vehicle is left-hand drive (ie, the steering wheel is on the left) then there are even stricter rules regarding importing.
You can most of the details in the Importing Vehicles to Australia Brochure.
If you are only planning to import the vehicle temporarily you can get by with having a Carnet de Passage en Douane (CPD), but even this will not be cheap — especially as you'll have to pay for transportation in both directions. There have been a few other questions here regarding CPD that you'll be able to find by searching.
Unless there are (very!) special circumstances, selling your car in Thailand and buying a new one in Australia will work out much cheaper than trying to transport it.
If you want to bring it back here (to Thailand) you will almost certainly have to pay import tax on it (even if it was Thai to begin with). Prices hold very well here with secondary depreciation almost nil (primary depreciation is when it is first bought and goes from new to second hand - this is still low in Thailand) and prices hold for more than a decade easily on well maintained cars. Also, if it was a foreign model (i.e. not assembled in Thailand) then it would have had up to 400% import tax applied to its price when purchased.
All this means it will be cost effective to sell it here (Thailand) and buy again in Australia - you will probably be able to sell a reasonably new car (say 5 year old) and still make money after buying new in Australia (like for like models of course).
There is no ferry - it is half the globe away! Like a ferry to South Africa! Only way is to ship it.
I can't tell you the absolute cheapest, but I can tell you it's not commonly done. It is however uncommonly done - by people on "adventure" trips, challenges, etc.
One current such adventure I could think of is "It's on the Meter - World Taxi Challenge". I had heard that they had travelled with their London Taxi from England to Australia so did some searching for how they got to Australia.
So I don't know whether you regard $3,000 as "cheap" or not. If you're on a weekend jaunt to Australia in some old banger then perhaps not, if you're fulfilling a childhood dream or drunken bet to drive to Australia in some bizarre or interesting jalopy and would be doing it anyway for the adventure, then perhaps this is a good ballpark figure.