These new bumpers are all polyurethane. Great, until you have to paint or repair them.
3M makes a unique urethane repair filler/patch which is the preferred repair method, but its pricey. If the Beemer (I have my own histories with some of them myself) did more than scratch the paint, they'll need to sand down and patch the gouge or crack. If the urethane is too badly damaged, it might well be cheaper to replace the bumper.
Doing the repair right (assuming spot paint just won't do) involves removing the bumper cover, cleaning and sanding the whole thing, any repairs necessary, and a repaint with the specifiied (paints that go over polyurethane are specially formulated to remain flexible)sealer, primer, color coat and clear. $600 at a high quality shop for the works.
Estimating the repairs without examining the bits is really hard, but that's close.
"You can never be free until you let yourself go."