For silver, though, there is a VAT rate to pay, which varies between countries, but I don't think it matters whether you buy from the EU or US in that case.
The difference is ~15%.
Only if bullion prices in the US were more than 20% cheaper than over here, this would be true.
But they're not.
What difference?
You pay VAT regardless of whether you buy from the US or the EU.
The VAT on silver
coins (not bars) is 7% in Germany, which makes it the cheapest in the EU, as far as I know.
So if you live in, for example, the UK, it's a lot cheaper to buy your silver coins from Germany, and have them delivered to you in the UK (and only pay 7% VAT), than it is to buy them from the US, and have them delivered to you in the UK (in which case you'd pay UK VAT (which is 20% AFAIK)).