Yeah, typical repair for M3's are crazy expensive. It cost me $5000 just to replace the back bumper when someone hit me. It was just a minor dent without any subframe damage. I ask them to replace my bumper since it was thru insurance.
Anyways, that M3 listed at Vaughan looks ok and $7k isn't that big of a deal as long as it drives great. However I would ask them to knock it down another $4-5K since it is a bare-bones car.