My mate bought a kite from the US for $800 and got hiht with GST but no tax.
I think it's all a bit hit and miss as I've bought stuff and sometimes had to pay GST and 5% tax. Othertimes I get it here with no customs.
You could always buy it and get them to hold on to it for 12 months so then you won't have to pay any tax

as you'll have owned it for so long. It'll also be worth about $50 in 12 months time