Re: What's a fair price for used exercise equipment?
As is true with any purchase...a fair price for an item is whatever it's worth to the buyer (and, I suppose, the seller

).
FWIW, my wife and I bought a used elliptical machine a couple of years ago through the classified ads. We got a GREAT deal on
THIS MACHINE. We plopped it right into the corner of our living room (near the TV) and used it ALL the time!

It is an older machine--which I'm not even sure is made anymore. As you can see from the flyer, it retailed for about $500. We paid $80! The battery compartment was a bit corroded but that cleaned up fine and the unit has been a great investment for us. We have since joined a gym but still use it on those occasions when our schedules don't allow us time for the gym.
Too late to make this a short story...but whatever price seems fair to you and the current owner will be what gets it done. But as long as you are committed to not turning it into a "clothes hanger," you will find you've made a good purchase!

Good luck!