I just got in a fender bender and need some info?

I was driving on the freeway and merging lanes, the guy infront of me came to a sudden stop, but I still had a good amount of space between us.. I slammed on my brakes but the tires skidded.. I hit him but not too hard... There were no dents to his bumper or cracks... He had maybe one scrath if that, and just some smeared paint from my car, but he rubbed some off so it's gonna come off... How much am I looking at paying to have his bumper fixed??... Or replaced if that's the case.... He said we didn't have to go through insurance and I could pay out of pocket, which I'd rather do... I just need some estimates.... He drove an Audi, I think it was an 06 or 07