[Perfectlap]

I would be inclined to call your insurance company and ask what sort of 'diminished value' someone who damaged your car would have to pay you. That should be reflected in the starting price of the car before you even begin to negotiate a lower price.
Personally, I would need a very very steep reduction to buy a car with enough damage that it had to paid through insurance. Around these parts some people would prefer to pay several thousand dollars in repairs then have their premiums go up and to keep it off the carfax record.