Hmmm It's one of those deals you're going to have to ask yourself how important is it to you. I mean with the bullbar and lights being there you don't really notice there not being a billet grille down there. I assume you plan on blacking it out to match the top one, so it wouldn't be really noticeable. Now if your billet grille was still polished and the lower one wasn't there, I'd say YOU MUST add the lower grille. I'm gonna say if you can score a lower grille for cheap then do it. I wouldn't spend over $45-$50 to add one.
99-03 Ford F-150 4WD/Expedition Bumper Billet Grille - eBay (item 190504746239 end time Mar-23-11 13:37:39 PDT)