Dear sir.
Only the cost of delivery itself may exceed 100-150 AUD.
However, I may propose you the way I usually work with clients oversea (and they are satisfied by this - I have successfully completed "remote" hardware projects in Australia, New Zealand, US and many other countries).
I may write the code and test it on a working prototype here (using the compatible components) and will help you to assemble it on your side.
The time and price depend on your skill on electronics, but I did it before with the real beginners.
My cost is for the code and approx. 10 hours of online help for assembling and coding.
Some part of job (coding, upload of the firmware, testing and debug) I can do remotely (using team viewer).
With best regards
Please, feel free to contact me in chat
Maxim Bulkowsky