A quick google brought up this guy in Qld http://www.spyderryders.net.au/products.html who seems to stock GP's... you'd need to find out what size they are though.
I did a bulk buy a couple of years ago from Calif Sport Touring for several LT riders in OZ... that made it worthwhile for the shipping costs (which is basically what the Spyder-guy seems to be doing).
There may be others who import them too... but $18 + postage will be a reasonable price from Spydy...
That's why I had to buy from http://www.casporttouring.com/
Unless one of the US guys feels inclined to buy & post for you.... which is probably the cheapest way to get from US.
Make sure you get 2 pairs... I had one split after about 18 months, just slipped a new "spare" on and all good. Postage won't cost any more for 2 sets.
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