off the charts and not that far off

[kjc0123]

What is the meaning of "off the charts" and "not that far off" in the following sentences?

Next to his rented Cessna was a Beech Bonanza, a single-engine, two-hundred-horsepower beauty that Ray could handle in a month with a little training. It flew almost seventy knots faster than the Cessna, with enough gadgets and avionics to make any pilot drool. Even worse, the Bonanza was for sale�$450,000�off the charts, of course, but not that far off.

[Clanad]

If I may add to andy hughes' offering; The word picture is one of something that is "charted".  One example would be, perhaps, a medical chart.  Recorded on that "chart", usually in a graphical form, are the observations of the medical people of the standard heart beat, pressure, etc., for the patient.  If the patient were to experience a heart attack, the information on the chart would go "off" it because the linear graph would not be recordable since the numbers usually used for such recording are to far beyond expected norms.  However, the person in the excerpt has determined, as andy states, that with some luck or financial manipulation the dollar amount may not be that farr off the chart...

[flaming]

Clanad:  I am sorry to disagree.  I thought it meant 'price charts' in the way that we can buy list price mags. which show a going price for a car.  I haven't actually seen a book price mag. for 'planes in W.H. Smith!   The 'plane talked about 'wasn't that far  off' (presumably)  the list price for a secondhand plane.

[Clanad]

flaming, while there are sources available for airplane values, It was my attempt to generally help in the understanding of the term off the charts... You may well be right in this instance, however.  It's difficult to understand the writer's attempt in using this cliche'...