I use a nVidia Quadro4 750XGL. I believe my company paid ~$200-300, but not sure. It was not 500. I have used other cards, but have had the best luck with this one.
I have also seen...one pc have certain fonts loaded and the SW user creates a dwg. Another user does not have the same fonts used on the dwg, then tries to edit them and crashes. Rare to see this, but have couple times.