Got my set for $60 but by the time I overhauled the manifold/valve, put in new orings, new burst discs, got a new set of bands and harness, refinished the tanks, had them hydroed, and spent a zillion non-recoverable hours of sweat and frustration I think they are worth more. Seen finished sets advertised for anywhere from $250 to $400. Just depends on how bad someone wants it, their condition, and what they are willing to pay. My 2psi. Others opinion may differ.
Good luck. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968)