Gotta agree with DruAde on this. It isn't rude, obnoxious, greedy or unreasonable to expect someone to pay for damage they caused. It's one thing if someone marks your 10 year old beater and another when someone backs into your unmarked 2 month old BMW 7 series or any relatively new vehicle. You can definitely cut her some slack, be kind about it and thank her profusely for being honest without eating the entire cost of repair/resale yourself. However, it's your bike, your money and your decision as long as you're happy with it.
Better living through chemistry.