As a newbie who just wants to build a decent little Matt Baker collection, my observation is that the high prices on recent eBay Baker books are being driven by just a few people.
A quick look at the bid history on a few recent eBay auctions shows that most bidders drop out at just barely above guide...and then 2 or 3 people push the bidding to multiples of guide.
This makes it tough for someone like me to build a collection. And people hoarding multiple copies of certain issues doesn't help, either.
I don't know about everyone else here, but one reason I collect Matt Baker's work is that he has been overlooked and should be exalted. Whenever I'm lucky enough to get a new Baker book, I share the art with everyone I know. Even my friends who don't collect comics think Matt Baker is cool.
WIth that same thought in mind, as I gain better-condition copies of certain issues, rather than horde multiples, I plan to put my lesser-condition books up for auction so others can collect and enjoy Matt Baker, too.
It appears that Baker books are at a high right now, due to a certain few people. If those people are bidding on books they need for their collection, that's great. If those people are simply speculators, trying to hoard great books that others could enjoy, that's not cool.