how can I find out the extent of damage?

If the carfax shows where the accident happened and the police report number you can get a copy of the accident report. It's public record. Or if the carfax shows where the vehicle was repaired you can contact them. Some repair facilities are more forthcoming than others though. Hope that helps! Jim

Not worth the effort to track it down. I advise you to find a better car not matter if this one is cheap.