What is the KBB?
You only have to buy one car, and there are always other used cars that come along in that price range. If an owner won't pay the $800 it would take to get the dent out, you have to ask how finicky they were about the mechanical maintenance (also expensive). I am not saying that if you have a dent you are a lousy owner, but maintenance is maintenance.
I would not buy a dirty car with dents unless there were no clean, low-dent cars (after ten years there will be a ding or two). Look for a cleaner car, and lower your risk. It will take longer, but hopefully a few months is nothing compared to years of happy ownership.