Audi A4 bumper?

[iTz Realiity]

I was leaving a parking lot and waiting at a light and a semi was making a left hand turn. The semi was going to hit my car so I ended up backing up. I backed up right into someones Audi A4. The tow bar went right into his bumper and I have no damage on my 2006 Chevy Trail Blazer, but he has a hole in his bumper. My parents are making me pay for it myself. I know it was a stupid move to back up. I've been getting this talk all day.
Here's a picture:

Would anyone know how much a repair for that bumper would be?