The watch manufactures will level the playing field at some point. This happened with a few of the big Australian wine growers a few years back when the UK price was so low that people in Australia were buying from UK wine merchants and shipping it back home.
The likes of Penfolds twigged to this and announced that they were substantially increasing the price of its premium wines in the UK to balance out with prices being charged elsewhere and to stop this buying back from the Aussies.
As such, a 2003 or 2004 bottle of Grange that was about £150 was suddenly £450 by the 2008 vintage and it still sold out very quickly.