Hi,
One thought occurs to me. If your grills are not broken, but merely sun/salt faded, why replace them? Why not paint them Flat Black with a paint made for plastics like Krylon Fusion -
http://www.krylon.com/main/color_product_viewer.cfm?productid=1751&sub_levelid=10&image_directory=/images/products/large/&image_name=fusion.jpg&image_alt=Krylon%AE+Fusion ? Their paint comes in Flat Black (# 2519) and costs under $8. If you replace them, they'll just fade again. But, you could just keep repainting these for a lot less money.
Send me a PM with your email addy and I'll send you step-by-step procedure for removing the Bumper Cover as a word doc. Hope this helps...
Happy Motoring!... Jim'99