Keep an eye on fleabay... whenever SRAM comes out with a new group (and i believe 22 is coming soon) some folks like to dump their old stuff for cheap. I got a Red compact crank and two sets of chain-rings for about 200 a year ago.
I'd probably look for the new Yaw chainrings if i were looking for new chainrings. They shift better than the older Red chain-rings. Obviously you need a whole new crank though.