The cheapest GTX 280 cards that are currently listed at Geizhals.at are selling for €497.63. The next cheapest stands at €499, while the most expensive is the EVGA's SSC, which is listed at a stunning €629.
The two cheapest, if you can call them cheap at €497.63, are coming from Asus and XFX. Unfortunately, they are just listed at this price, and still not available, but that is probably going to change soon. The most expensive one, EVGA's SSC GTX 280. is also not available, but Alternate.de claims that it can deliver it in 3-5 working days.

Quite a price for a card that doesn't even beat the older 9800 GX2, priced at around €400. You can find the Asus card listed here, and the XFX card is here.