Buying a graphics card..?

I was thinking of buying a graphics card sometime in the future…
My priorities:

  1. Very Fast rendering in Cycles.
  2. Modern games on highest graphics. You know, Crysis, GTA 4?
  3. ~300$ I guess…

Soo… I am a little not sure on how to go with this…
First thought - Nvidia, because it has CUDA. And CUDA is faster then OpenCL.
Then, Either take GTX 480, spend a lot and get a real monster inside… But maybe it’s a bit of an overkill and GTX 460 (which is a lot cheaper) is enough? Saw that people sell barely used 480 on ebay that fits into the budget.
What would you do?