I bought a mens and ladies 3spd SuperCycles for $40 at a garage sale last summer.
Both had SA hubs and Raliegh seats and I figured they were late 60's- early 70's by the date on the hub.
I bought a SuperCycle from the 70's that was a Puch or Iverson.
Value? Where I live (Regina) $10-$40.
Rarity? Not really as you can see them parked on driveways every spring when the garbage sales start up.
I would take the hub off without a second thought if I needed it for another bike.