Sorry bout all caps, but it had to be done

. Anyways, I went and checked out this mx6 v4 stick and the car was in great condition. Old lady driven so never beat on

. But to my question. The car has rust all around the rear left wheelwell. The owner said that it was a bad body repair job (someone backed into her in a parking lot), she had paperwork to show she was telling the truth. So how much do you think this would cost to fix? In one area the rust has eaten through all the way.
Damn this is frustrating. They'll sell it to me for 2400 and besides the rust spot it's in damn good condition.
answers?
thanks