I went to a importing company in Albury and asked them how much and biased on 100kg in a 1m square box it would be $1000
So you have the cost of the engine
+5% Duty
+Shipping and Insurance
=Taxable ammount
+10% GST on taxable ammount
So if its 1000USD and shipping is $1000 and USD=AUD you would be up for $2255
"Imported goods valued at or below A$1000
Generally, there is no requirement to pay duty and Goods and Services Tax (GST) on imported goods valued at or below A$1000, except for alcohol (refer to Example 2 where Wine Equalisation Tax (WET) is also payable) and/or tobacco products (refer to Example 4).
Imported goods with a value at or below A$1000 that arrive by air or sea cargo will require a self-assessed clearance (SAC) declaration to be lodged with Customs and Border Protection.
There are no Customs and Border Protection charges for making a SAC declaration.
For more information about SAC declarations see the fact sheet Self-assessed Clearance (SAC) Declarations.
Goods with a value at or below A$1000 that arrive by post do not require a SAC declaration."I dunno what they consider post, as i got leaf springs from rally design and I didn't have to pay duty.
Hope this is helpful
cheers