As it can be difficult to find stuff for the "good ole' times" (Continental Epochs 1 and 2; up to 1945) some guys have created a facebook group where only this old stuff should be traded.
Sure it has not the features of eBay and similar, but the group members are looking explicetely for such old-timer stock.
https://www.facebook.com/groups/224645526455045/ (https://www.facebook.com/groups/224645526455045/)
Language is mainly german, but I asked whether english speaking members would be welcome and they are. If help translating stuff is needed just yell...
If this post is not correctly placed or not ok... just move or delete it.