It's interesting how many on the auction house will continuously lower their prices and sell-themselves-cheap, pretty much giving away their wares to make minimal profits. For some this might seem ok, but those experienced know that it's all about profits and making as much of a profit-margin (return on investment - ROI, blah blah blah) as possible.
Personally, I stockpile item(s) on a bank alt based upon their value and sell when the time is right. Sure my gold will be tied up for a longer period of time but it'll take that item out of the market and will increase in value over time. Albeit, if there are ten thousand of the item you have, stockpiling and reselling might take a little longer than usual....but what's the rush? The gold will come. Sell at the right time when the value is at it's highest.
With TradeSkillMaster (TSM), you can setup thresholds to only sell items based upon a minimum value (which you set in price and it'll tell you if any existing auctions are 'below' your minimum and won't post it. See orange text: "Cheapest auction below threshold.") and also the quantity. There's nothing more annoying to a buyer than seeing a single-item listed 100 times by the same seller. This will actually turn them away and in some cases, will pay more for stacks if they see that. Knowing your market and having an understanding of how many items you should be selling at once of the same type is a science in itself. (blue text: "Maximum amount already posted.").
Yesterday I was lucky enough to buy Grakl's Gleaming Talisman for 25 gold! Yes, that's twenty-five gold (obviously a mis-listed item or someone didn't know what they had). I in turn listed it on the AH, for about 7,500 gold. Immediately I received quite a few whispers telling me it's not worth that much and they would give me 5K...then 6K, etc. Don't let people try to undersell your items....know the value and wait until it sells - do research and get what your realm and overall history of the value is from www.Wowuction.com. It sold tonight for what I was asking without compromise. I was pleased and this pushed me over the 100K marker! I'm 1/10th of the way to gold cap on this toon anyways...
The thrill is in the hunt!