There are no import duties on GPUs in EU AFAIK. So any price jumps may not be explained by that.
I sure hope you are right. That leaves the 21% VAT , then prices with a bit of profit for the reseller will still be around 309 to 319 euro.
I sure hope i am wrong about this.
EDIT, I looked it up, when the card comes from outside the EU, there are import duties whenever the price of the article is more then 150 euro(Netherlands).
The price of 319E to 329E seems more and more likely.
Another edit:
Typical tax agency.
At one webpage they say there are import duties.
Then i go to the page of the actual calculation and it say 0% for computer parts.
So, that is good news. That leaves the price only with 21%VAT added : 309E to 319E.