Sotheby's is having a baseball memorabilia auction on June 10. These auctions are always full of interesting things and this one is no different.
Some of the Reds related items:
Ernie Lombardi 1940 World Series ring
1935 signed Reds team baseball (and other signed team baseballs)
Ernie Lombardi 1938 National League MVP Silver Box
There's a ton of interesting non-Reds items as well, it's fun to look through the catalogue.