Gosch Nazi Flag 50x85 CM

Ahhh for once somebody used their head and actually posted decent photos of an item in question.
Your flag is the real deal, the manufacturers marks prove its not some post war repro I've far too commonly seen at some auctions and gunshows.
Flags in this condition I've seen average between $250-300 at gunshows. If it had original military capture papers saying it was a war prize would kick up the value higher.
Personally I'd keep the flag if its part of your families history, far too often I see grandkids or thoughtless relatives simply tossing or selling off things grandfather, dad came home from the war with without forethought or historical reasoning.
Large collections of such items could also be loaned/donated to a museum and displayed there for others to view, usually with a note saying part of the collection of (add military rank and name).
Hell of a nice find there.