Here it actually depends on which pseudo-private-public insurer you have. Most have age limits for coverage, the most common one being 25 or 26. The lowest seems to be 19 (what a joke, it's in the catalog for <=18), many don't cover it at all. Total cost (no discounts, since not covered) seems to be about 700-800 €.

> And Europeans keep saying how much worse the American system is.

There's a reason the comparison is always the average/median situation in the EU vs. the worst possible situation you could be in the US.