They won't deal with US sales taxes in Hong Kong, so the tax is applicable at your end IF the package gets stopped and checked. That can be a lottery as they don't check them all, you just have to accept that you may get a tax bill on delivery.
When DigitalRev sell to the UK, they have three ways of doing it, and the prices vary accordingly.
1. Tax not included, item sent from HK, if it gets stopped at customs it is the buyers responsibility.
2. Taxes ARE included and the item is supplied from DR's London HQ.
3. (less common, generally seen on their ebay listings) Tax isn't paid but if it gets stopped at customs then the buyer pays it but can send them the receipt and they will reimburse the amount. So, no risk but the sale is at a higher price than method no 1.
So, it is worth reading the details thoroughly, as they do make the tax situation clear for the price point they are selling at.
Also bear in mind that the warranty may not be valid in the US, so if any warranty work is required you may have to send it back to HK to be done. I think the lenses may be covered in the US, but not bodies, but check that out at your end.
DigitalRev are a good company, but do be aware of the potential issues with importing grey goods yourself.
