Redbook / Glass' guide prices

[fergus]

Has anyone noticed how these two publications have VERY different price ranges for the same model car?

eg 06 Territory turbo ghia:

Redbook trade in $31400 to $34700, private $36000 to $39300

Glass' Guide trade in $37000 to 43800 private sale $39420 to $48180

Both these mobs claim their information is the result of extensive research into both sales and advertisements for vehicles, but they must be doing their research on different planets to be almost $5,000 apart?

Which one would you use for the most accurate and realistic price?