I have no idea what these speakers are worth

A friend of mine recently sold two vintage Harmon Karden stereo speakers on EBAY. He sold them for several hundred dollars. That made me think that I could possibly sell the speakers that have been used as end tables in my house for the past 30 years. They are:

two Pioneer C5-A31-Max 40W
normal 20W
Impedance 16 Ohms
speakers.
I bought these new on 1967, and, as near as I can tell, they work just fine.

My wife bought two
University Sound ULTRA 1
3 way ducted speakers.

University Sounds was at the time of purchase (1967) a division of Altec - which was in turn a division of Ling - LTV corporation.

Both sets of speakers are in pretty much mint condition, and the University Sound speakers have not been electrically plugged in since 1973, but they are great for acting as a base for vases.

Our (adult, financially sound) son is interested in buying one of these sets, but we have no idea what they are worth.

Does anyone in this forum have a decent idea?????