Yes, ditto what I@M and Kym said. Any remaining differences in price after taking into account tax/georgraphy/rent etc relates to market segmentation strategies, ie pitching a product at a price point that a market will bear. Where the difference becomes too great, grey importers appear and undertake arbitrage.

Companies like Canon and Nikon are keen to maintain their market segmentation strategies (and higher profitability), hence discourage grey imports with threats of not honouring warranties. Where a product has been bought "in Australia" (eg an online shop with Australian ACN/ABN, with payment in Au$, even if product is being shipped in from abroad), then normal consumer product laws apply and a product has to be fit for purpose and of merchantable quality, regardless of whether imported through official or parralel channels.