Its around 80 bucks, I got the 2 peice and am happy with it, the 3 peice looks "better" though because it hides the small gap the 2 peice leaves behind.
You *could* run the 2-peice grill if you want to modify your stock GT inner grill trim.
All the 3rd peice in the kit is is that GT trim peice with a hole cut out of the center to fit the pony in. Take a look behind your honeycomb and you'll see the indent and even the holes for the screws.