Best graphics cards for scrypt(litecoin etc...) mining?

I have a budget of around $1000(including taxes). I don't want to build a rig, so I'm looking for a single card that will give me at least 850-1000+ kh/s, low noise and good ventilation. I'm very noobish at this, so any help will be greatly appreciated. Thank you in advance.
Thank you but it's very unlikely/impossible for the U.S. government to regular cryptocurrencies. And since the bitcoin/litecoin difficulty is high, I'm not mining any of the big coins. I have 40+ alternate cryptocurrencies, I got most for free now I'm trying to mine my own. Are the NVIDIA cards usually better for gaming or any other purpose than AMD?