This is in the category of IMHO or .02 worth. (Don't mean to offend anyone) Here goes...
Historically pricing guides almost always ended up being managed to some degree by those with the greatest $$ interest. I always come to this conclusion as up to about 5 years ago years ago my family (not what I did for a living) were well know antique/collectible dealers for several decades. In the print era every pricing guide was published by people who made up or inflated prices. Of course, along came Ebay, the "great leveler" and that made pricing guides obsolete almost overnight and exposed the chicanery that went on during the print era.
It's all what the market will bear - By the year, by month, daily, the Dow or by the phases of the moon or whatever. Right now, people are paying stupid prices for GEC, Northwoods - mostly on Ebay, but elsewhere, too. - (IMHO) this started to climb steeply about 18 months ago. A check of sold item for GEC on Ebay shows almost 70 sales in the $400 to $1000 range from mid May to today. All that tells me is that yet another block of buyers are forced out of the market - but hey, we're a capitalistic society and with it's burrs it's still the way to go. How long a trend will last or what market force or event will change it is anyone's guess. So, how does a guide fits into all this unpredictability and emotion?... well- I just don't see it as that useful.
I would, however, not mind seeing an accurate, easily accessible guide to all models, variations etc by number produced and date. Most of this info is on the GEC site, but it is cumbersome to access. In the spirit of saving time, an online book (with real time updates) or something in scrollable form would make an excellent reference for people to draw their own conclusions in a quick changing and variable market.
Again - IMHO