If it's been sitting, the grease may have hardened in the hubs and bottom bracket. Try to drip some oil into the seam between the parts that turn and the parts that don't, after wiping away any grit. Do it every few rides. Don't use wd40 or a similar product because it's more of a solvent and rust preventative than a lubricant.
I know a little bit about that bike. It was one of the nicer AMF bikes they had in the 70's. It has a lugged frame, three piece cranks, and center-pull brakes. Whereas most of the AMF bikes then were more like the Huffys with cheaper(heavier) one piece cranks, a plain welded frame, and cheap stamped steel side-pull brakes. Your bike is more similar to what a moderately priced Nishiki or Schwinn would have been like then. It is a decent rideable old ten-speed type bike.
You will probably want to get some new tires to replace those old dry gumwall ones and as Garage Sale Gt said try to get some fresh lubrication into the parts. Im sure you will get $80 worth of use out of it as long as it gets ridden.
There is one shown on the Old Ten Speed Gallery Barney’s Roadmaster Pro Tour | Old Ten Speed Gallery
It appears to be fairly basic (steel cottered crank set, steel rims, stem shifters, brakes with safety levers, hi-tensile steel frame), but nothing wrong with that. The fellow who posted to OTSG seems to like his. Falcon derailleurs? If the tires are useable, and the paint and chrome are in nice condition, $80 is probably the going market rate in many areas. Well worth $80 if you put some miles on it.