I found and fixed up an AMF Nimble and wonder what it might be worth. I'm guessing $50 to $75 on a good day, but don't have a real clue. This was a curbside freebie I cleaned up. A couple hours works and $12 for cables and brake pads, so I'm not too heavily invested. It's a nice looking bike and I figure it would make a good neighborhood cruiser
I don't know about the age, but guess '70s or early '80s. The bike's got a Shimano "3speed" hub and I found a thread that said hubs with that lettering were used during that time period.