HK is no longer the land of cheap Swiss watches because of all the mainlanders coming over to buy watches. IIRC, HK is has been the #1 market for Swiss watches (and beating the US) for several years now. You'll also get the same treatment in Singapore but I found the folks in Thailand (BKK) to still be quite aggressive with discounts.

The US is also pretty good (and there are ways to "avoid" paying taxes) and I always found Japan to also have good prices - at least when their yen was at lower levels.

I suggest visiting the TimeZone forums and looking at one of the Authorized Dealer (AD) sponsors. They can usually offer a good discount, you get peace of mind you're getting a genuine product, and as mentioned earlier, there are legitimate ways of avoiding paying sales tax in the US.