Scenario:
You ask a supplier to match a competitor's price (which is ~ 10-15% cheaper). You receive an e-mail in reply indicating they have agreed, sure, no problem. And then 17 minutes after their first e-mail, they send you another e-mail, saying succinctly: they've changed their mind out of fairness to their customers, some of whom spend hundreds of dollars per month.
For about 15 minutes, I was giddy as a school girl. Then the second e-mail arrived . . . just as I was about to place my order. How very disappointing, to put it mildly. I feel I should spend more money with this company so I can get on their "deserves good treatment" list. I wonder how much it takes. A clearly outlined tier system might encourage me to spend more money.
The upshot of this is, I suppose, if you are the recipient of a good deal from some of the companies frequenting this forum, I suggest you take them up on it with haste! Also, be aware of those who willingly price match, and those who don't, and infer accordingly. I would also suggest that the type of behavior I experienced from the company is very unprofessional. The profit margin on the item I requested a price match on is probably quite high. A simple price match as that would have eaten into perhaps 1/3 of their profit per item (assuming a fairly standard profit margin of 40%, i.e. cost x 1.67 = final selling price).