A few things stand out:
Baush and Lomb (at least triple-) convertible Protar lens. Expect maybe
$100-300 for this alone, depending on how clean it is and whether the shutter works. Also, how much it covers, I'd assume that it at least covers the camera it's mounted on, is it 4x5", 5x7", or 8x10"?
I think I can just read it, says 11 3/16"?
here sold a similar one in a dead shutter for $200
and
edit: more here too
These film-holders look about 8x10" size. Expect $30 each minimum, maybe up to $60-100 if you can prove that they are light-tight.
I also saw a lot of other film holders, like 4x5 and 2x3 too. They'll all be really easy to sell anywhere, just sort them into groups of size and type/age (newer plastic sell for more than older wooden). keep on the lookout for weird ones that only have one side, they could be for glass plates (rare and possibly more $), or 'film packs' (noone wants them and worth almost nothing).