They won't have it. Hobby stores that sell model kits and remote control gear will be your best bet to buy over the counter. I've always got mine on ebay.
I think I know some shops in Darwin that sell Hobby supplies so I'll give them a try, I think there's one in the shopping centre in Casuarina, anyway, I guess it won't hurt to do some shopping around, I'll give eBay a try too, cheers pablopepper.