I doubt there's such thing as fair price. Or, to define somehow, fair is price both seller and buyer agree. To somehow get closer to real numbers, let's start with basic price US$9.99 for "nice Lynx 14 from estate sale, sold AS IS".
Let's assume, seller have put array of pictures and responds well. If we ask questions and get answers, we can add some sum for each positive answer, and so go on.
- Is lens barrel and lens rim not bent ? YES. Add 10-15$
- Is lens clear, no fungus, no scratches, front and rear elements ? YES. Add 10$
- Does aperture works as supposed ? YES. Add 10$
- Does camera winds and shutter opens and closes ? YES. Add 5-20$, how you rate this.
- Is battery compartment clean, in case of 14e it even opens ? YES. Add 5$
- Is RF clear and RF patch is clearly visible ? YES. Add 10$
- With installed battery and pressed "switch", meter needle reacts to controls ? YES. Add 5-15$, how you rate this.
So one can continue with another, incl. cosmetical, issues and build price he's ready to pay. Mostly this depends on how many cameras are on market at the moment (I'm sorry for so stupid sentence). To say, seller loves this camera much as he bought in 1973 and is ready part with it for us$100, but I can get very similar for, to say, for us$50. Is it worth to pay extra 50 bucks for chance to see camera and try all controls before buying ? Answer is yours, but last feature for so many is main selling point. If one can get camera for sub9.99 then one can win, can loose and and not cry if camera is junk. Really hard to say exact number.
Well, after seeing number of 14's going off for ~us$50 during a month, I immediately snatched one with "buy it now" for 25, but I'm cheap and try to buy cheap but this time I just went for "want it right now". Some people here have got their 14's for 9.99 with patience. See - we again come back to how badly you want piece of gear, right ?