In the US you can get a bottle of 500 ibuprofen 200mg pills for about $10.
So for your case that's 8000mg for 3 euros or .0375 cents a mg
In the US that would be 100,000mg for $10 or .01 cents a mg.
So 3.75x more expensive not factoring in the Euro being higher on the dollar.
But it's not even about the price, it's the fact that it's just hard to find a large bottle of it here in the EU at all (at least the Netherlands where I am now). I've never really seen it in stores. I much prefer buying a bulk bottle that lasts a year or two easily.