I think your last sentence here is the key. I can't tell you how much money I have made by playing the players. if i see the "king" of our auction house has the lowest price on something I have a lot of, I undercut him by about 20%. That is the price point where I KNOW it will sell because HE is going to buy it to relist.

I just did this with Runed Living Rubies last Tuesday. He had about 20 of them listed at 70. I had been stocking up throughout the week and proceeded to post a dozen of them at 55 each. I then got on an alt and whispered him that somebody had flooded the auction house and undercut him. Two minutes later I had 660 gold in my inbox and he had 12 new Runed Living Rubies in his bank. I got my money now, he gets an extra 180 if he sells them all this week, which he will, and everyone wins.

Except the poor saps paying 70 gold for a Runed Living Ruby. But I guess that's what you get when you have one guy on the server with 600K gold spread over 4 toons. He gets to make the pricing rules.