On '70 grilles, the cheaper ones typically only come with the bare plastic grille, headlight bezels and 4-piece outer moldings. The $1000+ ones I've seen usually are painted, and have the Plymouth emblem and some come with inner trim (red bars or Gran Coupe/AAR rectangular moldings). The most expensive ones also have the parking light assemblies with them. I have had a couple of the Goodmark grilles (about $500 ea), and they are unpainted gray plastic. The moldings fit on the grille and headlight bezels pretty well, but they didn't make the moldings on the headlight bezels properly where they fit over the grille moldings. I had to "carefully" grind the underside lip off the moldings on the ends where they fit over the grille moldings. The grille seems to be the cheapest part. All the trim and parking light assemblies are the expensive parts! If you need a complete grille, the more expensive ones (complete assembly) are probably cheaper than buying all the pieces separately.
I don't have any experience with the '71 grilles...