The DTM site isn't loading for me for some odd reason. If it's just the kick plates like Alan got, I'm pretty sure you're gonna have to check overseas. If not, ask BMA or your local BMW dealer for OEM M5 ones!
Oh, BTW, lots of E34 guys are getting in on Shadowline trim. I dunno if you used the tape or not, but this is OEM Trim. It's from abrahammotorsports and the group purchase for each person is $379. A lot better than $600 per side from the dealer.