I inherited a bunch of those. Had a garage sale and put a sign on the table that read, "Instant Ancestors." That was at least 15 yrs ago. I think the ones that had the rounded glass sold for $35. to $65. It depended on the frame and size too. I had lots of small professional photos that were of little girls or families dressed up. Those sold for $5 to 10. with no frames.
It's too bad people don't mark the back of their photos for their relatives. I have a stack of family photos that I have no idea who any of them are. One is a group of men with long beards and all on horseback. I can't get rid of 'em because they're family, but I don't know anyone alive who could possibly ID them. After Hurricane Camille, I started marking the back of my photos with who they were and my relation to them.