Michael Fremer knew Ricker and wrote a nice R.I.P. for him. Michael is pretty approachable and he might give you his opinion about the speakers if you contact him.
Otherwise I think you will have trouble selling these speakers for a significant amount of money. Your best bet might be to familiarize yourself with the forums that specialize in recording like Gearslutz and target your listings to people who may know who Ricker was. Another option is Reverb.com which specializes in selling music and recording gear. Another rabbit hole would be to research if there are any recording museums or if there are collectors of vintage recording gear. This is a long shot but Dave Grohl might be the kind of person that would be interested in preserving these speakers. He bought the Sound City console and he is a known collector of vintage gear.
Unfortunately no-brand-name rarity is not a good thing in audio. It would be neat to be able to say, "The Beatles were mastered on these speakers" but it probably doesn't lead to a high value. Good luck and I hope you find a good home for this gear.
Otherwise I think you will have trouble selling these speakers for a significant amount of money. Your best bet might be to familiarize yourself with the forums that specialize in recording like Gearslutz and target your listings to people who may know who Ricker was. Another option is Reverb.com which specializes in selling music and recording gear. Another rabbit hole would be to research if there are any recording museums or if there are collectors of vintage recording gear. This is a long shot but Dave Grohl might be the kind of person that would be interested in preserving these speakers. He bought the Sound City console and he is a known collector of vintage gear.
Unfortunately no-brand-name rarity is not a good thing in audio. It would be neat to be able to say, "The Beatles were mastered on these speakers" but it probably doesn't lead to a high value. Good luck and I hope you find a good home for this gear.