If you haven't tried yet, email the guys over at Morad's:
Morad Parts Company - 3800 Motors, Transaxles, & Stock Parts

I got two of those pieces from them a while ago. I'm not sure if they still sell them and it isn't all that cheap. It is the only option I know of besides buying a whole door panel. I've heard of people trying to use door edge guard trim but the pics I saw didn't look too good IMO mostly because it had a glossy finish.