I agree. However, it terms of valuable posters from the era, most of the ones we could mention would be for those films that survived:
Birth of a nation, The Gold Rush, Ben Hur, The General, Phantom of the Opera, etc.
The only lost film I can think of where the poster gets major attention (and sells high) is London After Midnight. Can anyone think of others?
Jay (and Paul), wouldn't you think that posters from that era (whether they be lost films or not) that included actors that are well known, even today, would still command a decent price? Chaney comes to mind, as he has is collected across several genres (silent, early horror, for his makeups), Pickford, Fairbanks, Chaplin (much of who's poster material comes to light now and then), Griffith films, Murnau?
LAM has certainly been the grail of lost films. One of Chaney's earlier films, called
A BLIND BARGAIN (1922) is also lost. I havent found a sales record for it's OS. Chances are, it would go for less, as it was pre-Hunchback and Phantom. But, being Chaney, it would still have tremendous appeal. Chaney also played a dual role in this film, as well:
But I think it is also true that for lost films, a poster may be the only remaining visual record (aside from possible script or "office" type material) that has survived -- so valuable or not, it is important that these are preserved and conserved, if necessary.