They're not worth much. The bodies are interesting and they're cool period pieces. I like them, myself. Electronics are usually "OK" provided they're not scratchy (but pots are easy to replace) and pickups are adequate but nothing great. Necks can be wonky, but if the neck is OK you have a playable bass that's different-looking and kinda fun.
IMO best use for those is to mount flatwound strings on them and use them for a period sound with classic rock or blues.
"The best way to tell a lie is to tell the right amount of the truth, and then shut up." Robert A. Heinlein