Here are the only recent 1914 sales I saw on ebay (not including Heilmann for over $700)
www.ebay.com/itm/221237963192 JJ Clarke
www.ebay.com/itm/271217048587 common
I mostly only look for 1916, which I almost never see for sale,(no 1916 on ebay recently), but if I do, they look and sell for about what these 1920's sold for...
www.ebay.com/itm/251292632766