They are worth whatever you, or another buyer are prepared to pay for them.
When I worked for a stereo shop in the 90's, the guy that owned the place was infamous for being a wheeler dealer....a very high strung, high blood pressure inducing individual.
Quite the character, but...he was a pro.
We took in used speakers on trades for new ones.
One day I came in and there were a pair of Dahlquist DQ10's sitting there he took in the night before.
I made the mortal mistake of asking "Hey Fred, what are those things worth?"
He bolted up to me and got about an inch from my face...his face turned beet red, and veins popped out on his forehead and neck.
"It's not about what they are goddamned worth, boy...it's about what I can goddamned get for them !!!"
I won't even tell how one night he locked the front door and wanted to fight back in the showroom...he was twice my age.