€660+
We've seen that VGA e-Geforce 9800 GX2 Black Pearl water cooled card is available in the German market, and if you don't mind waiting for day or two you can get it for around €660.
The geizhals site doesn’t really shows that the card is overclocked much, but we are sure that you can push that card quite a lot, at least when you use a water cooler.
The cheapest air cooled 9800GX2 sells for a bit more than €400 but if you want to get the fastest card water-cooled than you can only get 9800GX2 for about €660 or more.
If you want the fastest water-cooled 9800GX2, which can easily be described as possible the fastest card on the planet, you can get one here.
