I may be mistaken but it looks quite similar to a 30-30 mount I used to have on a old Winchester. Value,,,,???? What someone that needs one will pay I guess, I'm not a good judge on used prices. It also appears to have an additional bracket(the lower portion) , mine only had the upper part for the 30-30.
I do remember those from "back in the day" and if I'm correct they had several different lower sections to adapt to several different guns. I've had that same mount on Enfields, Mausers, Marlins lever guns(before they were tapped) and Winchester lever guns. I think I still have one kicking around too if I'm not mistaken.
They were a pretty good mount though. Lots of those old mounts were very high quality and STILL work very well,,and much better than the cheap China chit that's out there nowadays.