A simpler grill and much cheaper solution is to use gutter guard.
I used the black plastic kind from a roll. I think it cost a whopping $5 bucks, and I have enough to do about eight cars. The only pricey bit is the black zip ties as they cost about $2 bucks for a pack of 40. Just cut off a three and a half foot section and zip tie the mesh to the back of the grill. It will nicely conform to the curve of the bumper.
Oh yeah, you'll have to remove the bumper to take off the three louver grill.
I'll post pics if anyone is interested...
BTW: The stock plastic grill doesn't weight anything. The only reason you would want to change it is for looks or extra protection for the condensor fins. Mine was the latter.