The best way might be to find a black grille in a parking lot, then wait to talk to the owner and ask if he would like to upgrade to chrome for a non cost swap. I bet most would do it as the chrome cost more. Or make a post in the general forum asking if anyone would want to swap their chrome for black.
honestly i have tried that... waiting in the parking lot. problem is, the trucks i find with a black grille out here are all commercail trucks, and they wont let me just do it... lol thanks for the idea though.