Ah, f'n horrific isn't it?
The short story is a great body shop could replace the bumper jacket and repaint for over $600 US.
Here's my story:
I did the same thing within a month of buying my 2002 325Ci, same shocked reaction, utter disbelief. In my case, the bumper jacket (the part you see) was unhinged from the body, dangling in a most ugly fashion.
I didn't go to the dealer knowing they would ONLY work on it if EVERY part was perfect by the end of the labor. So, I went in search of a local body shop and found a brilliant 70 + year old frame straightener who replaced the black air dam you mentioned, and repositioned the bumper for $140 US. I was soooo grateful!
Then I got sloppy and did it again on the other side. Same deal.
Well, my man actually died the day before!
So I searched again to no avail. No one would "repair" it, only replace and repaint it.
I surrendered and went to the dealership recommended shop, and they surprisingly offered to repair it for $190!
Moral of the story:
These babies are expensive to own and this is just part of the upkeep. I will be MUCH more cautious, but won't beat myself up when I fuck-up next time. The lower front end looks and performs well, and she begs for better care.