As I said, I do understand that. However (and I should have noted this in my original comment), I always tell them up front that I don't like to haggle, and would like their best possible price up front. I also tell them that I am comparing it with at least two other vendors (I always get at least three estimates). Therefore, when they do reduce it, they were lying the first time.
I am always very honest with them, and expect the same. Heck, I don't even hesitate to pay them when they screw something up. I pay them promptly, and then hope they will do the right thing.
While items and services don't have a "real" price, they do have a "best" price.
EDIT: I'd also like to add that, while the article focuses on consumer pricing, I am different when it comes to B2B pricing. E.g. I would quote a successful law firm more than a mom-and-pop shop for consulting services. Back when I was an entrepreneur, I actually lost a couple of contracts because my quotes were too low.