FCP Graphics card for custom built computer? Under $200?

Hi,

I am building a custom computer (just learned the term hackintosh today!) and have been reading about AMD vs NVIDIA, etc. Seems with right drivers, etc, both types of cards can deliver similar performance.

I work mostly with audio but will be doing some video editing. Nothing insane, but I still need a fast system so I can work efficiently.

I see benchmark scores on this site and a lot of the well-performing cards are $300+. So the question is, what is the best performing on-a-budget graphics card that will work very well with FCP?

Thanks!