what are your system specs, including PSU?
Are you going for most powerful/best graphics, dx11 all that stuff.
Shooting off the hip here I'd say if you want a dx11 card go for a ATI 5770, its 45nm so it runs cooler, had dx11 and isn't all that bad.. i have one and haven't had a game i dont run on high if not max settings (though crysis is a pig for graphics!)
ifyou're looking for most powerful its probably a ATI 4890.. its only dx10, but has a ton of power.. runs a little hot, but if you overclock it you shouldn't have a game it cannot play (except dx11 titles, which will probably still play on dx10)
Also the 260 gtx on the nvidia side isnt bad at all either and I think in that price range.. though this is all speculation and mostly from US prices since I didnt have time to look em up..
goto newegg.ca and check out their prices on the mentioned cards.. also the 5750 or 4870 wouldn't be all that horrible either.. if the prices are too high