I agree! But, I'm surprised on this one to hear of two online estimators showing $19K for this plane (I haven't checked them myself). In my experience, those estimates are usually higher than what I see in the actual market. These actually appear to me to be right on the money to a couple grand low!
If I look at the asking prices on 10 similar airplanes, I can throw out one or two each of the high-ball and low ball numbers (they will be obvious). Average what ever is left, and subtract 10% (for those sellers that might negotiate). That gives me what I think is a workable market range for a basic airplane.
