OK here's my experience with customs. I ordered a set of four QA1 shocks and matching springs from the States and submitted a declaration of "US Origin" for the goods (thanks Geoff).
When they arrived I got a call from the Fedex broker and he pointed out that the country of origin for the springs is actually China. No great loss there @ $150 in total. Probably made from Aussie steel anyway!
The shocks came to about $1250 AUD and I paid GST on that ($138) but no duty. There was $8.14 duty on the springs (5%) and another $20 GST. They charged $40.20 for "import dec N10 air charge (goods value > $1000)" and $15 for "AQIS - entry charges air".
All up $220.58 in fees on about $1400 worth of goods, of which $150 worth didn't escape duty.
I tried the "1965 AC Cobra" trick and was told it had been changed to 1962. Maybe they got sick of all the Cobra-philes?
Sambo