it's all relative- they are worth what YOU are willing to pay for one- and can range in price from $25 right on up to $600---or more
if you are (in the market) for a featherweight- you should set yourself a budget---how much you are willing to pay for one- then look until you find one in your price range. i would think one in great shape- working well- well maintained would certainly be worth a heck of alot more than one that's not been taken care of- or is not working- one you have to put money into before use...different locations seem to have different price ranges too...but only you can really decide what one would be worth---to you.