OP, the bars are made by Setina, and they're pretty easily adapted to just about any vehicle you want. Can be had from Setina's website, or, you can yard one from a Crown Vic, and occasionally, they pop up on CL.
I found one locally for about $100, but, that's also because Setina is local, too.
GT Spec makes a full undertray, as does another, but I can't remember the name, currently.
I want LED taillights and a hi-flow super hush muffler.