It looks like the error is in the CL; you only need a CL of 7 to use DD, and using that number instead of the given CL 9 produces the given price. Not sure if it's deliberate or not, the only real effect is to teleport 760 instead of 680 feet.
Dimension door lets you take another person per 3 caster levels so the difference between 7th and 9th level could be very important to that 3rd person.
Dimension door lets you take another person per 3 caster levels so the difference between 7th and 9th level could be very important to that 3rd person.