How much would a good video card cost me?

I've been having trouble with my video card lately. My problem is it sucks. I play a lot of video game sand all the video games coming out are a little too good for my video card to handle. My computer's standards exceed the minimum requirements for most game except for the video card. So I was wondering how much would a video card cost me that would let me play games like Magicka, Portal 2, Bulletstorm and other stuff like that. Thanks in advance for answering.|||More then you can afford