so per person has to be more than 300$ on an single invoice or under 1000,
if's over they process it and put a note and if you bring it back you have to pay max excess duty, it's a real pain (if they even go though process at all usually they just say no)
If your leaving permanently then it all ok
From site:
https://www.border.gov.au/Trav/Ente/Tour/Are-you-a-traveller I claimed a TRS refund for some goods that I now want to bring back into Australia. What do I need to know?If you are aged 18 years or over, you can bring in up to A$900 worth of general goods into Australia duty-free, or A$450 if you are younger than 18. Families travelling together can pool this allowance (so a couple with a child can bring in a total of A$900 + $900 + A$450 = A$2250 worth of general goods into Australia without paying duty or tax). This is called your Passenger Concession.
General goods include gifts, souvenirs, cameras, electronic equipment, leather goods, perfume concentrates, jewellery, watches and sporting equipment.
If the total value of the goods you are bringing in is greater than your Passenger Concession, including goods for which you have previously claimed a tax refund under TRS:
you must declare all of these goods
for goods where you have previously claimed a tax refund under TRS, you will need to pay that refund back
duty and tax will apply to all items of this type, not just goods over the limit of your passenger concession.
Penalties may apply if you don’t declare that you have goods in excess of your concession.