I know several collectors in Washington, but here or there...
If on gun broker than probably 1/3 of the people here have already looked. If on a dealers site, more so.
I suggest you buy from a well known dealer with a good rep. Although I always say, before buying anything, decide on what interests you. Can't be a "Luger" because variations are many. WWI, WWII, weimar, army, police, shooter or Collectable.
And if you expect a FFL receiving to appraise it for you, either I'd expect to pay them, or...
Buy books, buy from the forum, buy from a reputable dealer. I would say EVERY collector has bought something in poorer condition or something wrong with it, to include myself