Establishing value of Nazi flag?

Paul "Yank" Edward Neal spent 4 years in the European theatre during WW2. He brought home 4 battle stars, a limp and a Nazi flag from a town he helped liberate. For decades the flag remained hidden away. Even his closest friends did not now of it's existence. It's very eerie to look at this flag.....knowing where it has been and the horror it created. My wife and I have decided to sell this piece of war memorabilia. It has never been of sentimental value. We've been trying to establish value. Nobody seems to know. Any ideas or links to ideas or buyers?