Approximately how much will it cost to fix this dent in back of car?

The back door/hatch work perfectly. It is cosmetic.

It's going to be expensive. They are going to want to put a new hatch on it. Bondo is almost out of existence, drill, slide-hammer out the dent, and Bondo. And is not acceptable to insurance companies because it does not last. Then match paint, probably re-use glass. Sorry I can't give you a Dollar figure but be sitting down when they hit you