I think its because of shipping and import fees thanks to your government. Davis sells at same price to everyone.
Well, intercontinental shipping which typically ends up by airfreight is certainly a very significant cost for something like a VP2 box (or a carton of four units, which is how they come trade). Import duty is a factor but usually just a few %. Maybe you're thinking more of sales tax, which in many countries is very significant eg 20% and must, by law, be included in prices quoted to retail customers.
Then there's the international business model that Davis use, which is - with the odd exception - to have only one distributor per territory. Resellers typically buy their stock from their local distributor and hence two lots of margin have to be added in.
Another main factor is support. Providing support is expensive. In the US, Davis provides direct support and so AIUI there's no necessity for US dealers to factor in support costs. Outside the US, the dealer or distributor provides the support and this can add another 10-20% to pricing.
There are other factors too like currency fluctuations, extra cost of doing business in many countries because of things like mandatory payroll taxes, pension provision etc for staff.
