Mobile Tradition apparently have every piece of sheet metal, but you could buy a fully restored e12 for the price.
Pete K
'75 520i (track day special)
'81 M535i (dream car)
'79 323i (wife's little cruiser)
'02 320ci/330ci track car (b30 swapped 320ci)
'97 Ford Laser (1st ever new car)
You'll probably have a better chance of finding someone parting an E28 in a non-rusty area. You might be surprised to know that between an '81 E12 and the entire E28 run, the floorpan is just about exactly the same.