How do American retailers stay in business?!

[NobleSixSeven]

So I started my fountain pen hobby as many people here through Goulet Pens, but as I delved deeper into the field, it seems that there is a HUGE markup in both pen and ink sales buying from a North American Retailer compared to a european one:
FOR EXAMPLE:
A Pelikan M1000 is 700-800 USD PLUS TAX ~ totals 800-900 USD
A Pelikan M1000 at Appelboom is 530 USD NO TAX. At CultPens it is 404 USD NO TAX.

Thats almost double the price!!

Same thing with inks:
Diamine Ancient Copper 50mL is $15 PLUS TAX at Goulet, JetPens, Goldspot, etc... but it is 7 bucks at La Couronne du Comte and CultPens..


If you take the price of European retailers as the norm, then US retailers pricing is absolutely exorbitant.
How is the pricing justified?