That's a good question, and I don't know the answer. I just remember following a thread when I had my C6Z a few years ago. Another member needed a new fender due to a minor accident and the fender was $3k, so the prices have come down at least from 3 years ago.
My wife is working on a diminished value claim through Geico right now. They have a separate department that handles diminished value so if you have not already done so ask your rep to set up a diminished value claim. So far they have been a little difficult to deal with and are drawling out the process. The repair work was good though.
From having dealt with this in the past when trading in cars the dealer only sees that there was an incident in the past on a certain area of the car and it does not say to what extent the damage was.
Diminished value is hard to determine and almost subjective in CT because there are no laws on the books. I'll see how far I can get wit that.
The shop worked up an estimate for the repair - $2700. The outer fender is safe, but the inner has a broken tab and needs to to replaced. Then some prep and paint.