Variation (Range, Quartile, Std Dev, etc.) Source for Flipping
Let's say you're flipping stuff on the AH. You buy stuff at or under 75% DBMarket, and post with a min post value of 80% DBMarket. If that 5% difference is too small you might end up loosing gold, if it's too large you'll miss opportunities.
Some items have a much smaller variation than others. That 5% difference for a Chaos Crystal might be 5 Gold, but 5% for a rare battle pet could be 5,000 Gold. The Chaos Crystal might have a fairly steady price, but the battle pet might vary wildly.
If there were a "DBStdDev" for instance, or a "DBRange" (maybe the average of the max - min from Step 3 of calculating the DBMarket value?) then the purchase price might look something more like DBMarket - 0.2 * DBRange, and the min sell price might look more like DBMarket - 0.1 * DBRange. That would help to mitigate the risk of targeting a % gap between buy and sell that's too large or too small.
It's just a thought. Thanks for all the work, this is my favorite addon.