This has been brought up before. No one right now makes any repop window trim and new ones are just about impossible to find. best bet is used and good used ones can be found and reconditioned. mps auto salvage, prestige mustang parts, etc are some sources if you can't find anything local.
You buy repo parts from the repoman. however, i'm sure you're looking for repro(duction) parts, LMR is the way to go when you can, but I'm pretty sure they don't have the window trim for the back and I'm not sure on the windshield. Junkyard and refinish it yourself.