Auto body repair & detailing: fender-bender this morning, pontiac grand prix, alignment problems

Question
Hi, Mark.  I was rear-ended this morning in my 1999 Pontiac Grand Prix coupe by a late model Toyota Corolla.  I was stopped and he was going maybe 25mph.  There is obvious cracking on my rear bumper around the license plate area but no other obvious damage.  We exchanged insurance information but he would prefer to handle this with cash.  I told him I needed to figure out how much the damage would cost first, but I will call him before calling his insurance company.  I may have been imagining it, but I thought I felt some increased vibration when going ~70mph as I continued on my way to work.  Is it possible for the accident I described to affect my alignment or something else that would cause vibration?  If so, I imagine I should probable refuse the cash offer and report to insurance, right?  Also, do you have a general idea as to the cost of replacing a rear bumper?  My car is kind of a rare color (gold) so I would probable need any new bumper painted as well.
Thanks!

Answer
Rochelle-

It is almost never a good idea to settle for cash. You may refer to my previous answers for details. I answered a similar question previously. You will undoubtedly have additional hidden damage that is not evident until the bumper is removed from the car for a real inspection. Often things like the muffler/ exhaust system could be damaged and or structural damage. Usually not suspension or alignment problems however, only in extreme impacts. You may just be hyper sensitive to the behavior of the car since the collision. Bumper cover replacements can range from $500 to $1200 depending on how many of the bumper components are damaged. Cover only maybe $500- cover, absorber, reinforcement, could be $1200. If you want to forget the damage and just cash out you will want to get an estimate for everything that is visible.  Good Luck! Mark