The triangle is about $16 USD new from Germany...I don't know what I was thinking when I said it was close to $70 !! Sorry.
Bracket from a US dealer is about $6...they list the part for 400Es but not the 500Es ...wierd. I'm pretty sure its the same for all W201/124s though.
Install looks good doooode...thanx for taking the time to share the pics; makes it easier for the rest of us.