Splitting hair?
It's well known Apple offers no discounts, except a small educational, and there are no Apple "Grey" markets.
Hong Kong is known to be a "shopping haven." Merchandises pass through HK without tariff.
Without checking with the United Nations, am pretty sure buying a MB in Hong Kong cannot be beat. If ur already making a trip that is, and not doing this specifically to bring back ONE laptop.
Splitting what hair?
Well you see, I live right next to Hong Kong and go there every couple of months, I don't know what the prices are elsewhere and while I know the prices in HK are very competitive I have no idea on the prices in other countries that I don't frequent. I therefore dare not claim that Hong Kong is cheaper than "location X" as I honestly don't know.
Perhaps Hong Kong is the cheapest, but I've not personally bothered to go country by country checking. The price difference between the Mac Air lower model is only about $60 between HK and US, and that could easily change with exchange rates.
I simply choose not to make any assumption and to give the facts that I can at the time of posting. That without knowing his/her country I can't say whether it's cheaper or not, and then including a link to the actual prices in HK.
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Do they sell them with the same keyboards and power cords etc as they do in the US?
In Hong Kong you can get both the Hong Kong style charger and the Chinese style charger (2 vertical prongs I believe, though China also has a 1 vertical and 2 tilted prongs type).
They may have others, although I'm not certain