Wish I could help, but can't. I don't know much about them, not interested in buying or selling them much. I'd try to sell them as a whole, then in groups.

Here are some I saved and put on a web page of mine:

Vintage Postcard Invitations for Poker Game Card Party
Postcards c. 100 years old

Click here to see over a dozen of them: http://www.antiquegamblingchips.com/PostCard.htm

Robert