Rather than deal with vague warranties, grey market or unknown (to me) vendors, I purchase in the country I live in. Fortunately, my wife and I split our time between the USA and Switzerland. Both are low price countries. I check Hong Kong prices every now and then for lenses. Either no savings or not enough to bother with.
One also needs to keep in mind shipping into many countries can be outrageously expensive. By the time I pay the Swiss post office administrative fees and customs charges, I've added 30% to the price of an imported product. The EU is even worst as their initial prices without VAT are high to begin with. So unless I purchase locally in Switzerland, all of my buying is in the USA. No post office charges, typically no customs charges as the system is full of holes -- a typical US government run department.
Looking at price instead of acquisition cost is a poor approach. There are still a few countries that support free trade -- the 3 mentioned above. However, for photography, markets are protected, distributors still control prices and governments attempt to kill imports with all matter of fees. So searching the world for a better deal based on price is usually a waste of time.