About the only gripe I have with Edmund's price guides is the fact that their software is not sophisticated enough to Grey out items or combinations that are not allowed.
On some vehicles, especially those with a lot of "package" options, it becomes real tedious to configure a vehicle....
What I MOST like about Edmund's data is for the last 7 years the invoice cost and actual cost of the different options has always been right on the money...
Hell, when I researched my New 05 King Ranch F350, Edmund's had better data on option costs then the FoMoCo new truck configuration site had...
In fact the Ford site has been hosed up for about 6 years now despite my sending them detailed feedback about what is wrong and how to fix it.... Hummmm, sort of like IB's SmartUSA site, but that is another rant elsewhere
I tend to think Edmund's has folks who research these things and in the absence of real facts, they generally make good estimations
Thus I believe the $600 destination charge should be real close