Hi skip, sorry I just checked my messages. The roof spoiler you're referring to I got on E-bay. I'll give you all the info here. I gotta tell you the paint matched perfectly. Even the new shark fin that I had a GM dealer paint for me wasn't as perfect.
The Seller is: bmwoemshop
I paid ~$80.00 dlivered and that included the fantasic paint job with 4-6 coats of clear coat.
Here's the one I bought (only SGM) - you just tell him what color you want, (WA708S) & he matches it and sends it out in 3 or 4 days. Ebay Item number 290414435920.
I couldn't be more pleased. It attaches with silicon glue if you should ever want to remove it. I used RTV.
Let me know how you make out.