I would say dealer may be avoided, as they might charge you a lot.
2ndly, it might also be possible that they get this work done from some after market shop, and claim that they did the work themselves, and when everything is done, and they hand over your car to you; they charge you a lot.
So why not have the work done yourself?
Bumper repair is not expensive or technical, unless / until it is shattered in to small pieces.