But the fun part is that they don't always match up, in fact they actually hardly match up in my experience. Do the math and you'll see these match up pretty well. At the time I write this Greater Cosmic Essences (Greaters) sell from 11-18g consistently. If you're paying attention you can post remaining inventory at higher prices and they will sell, instead of undercutting the cheapest post.

When Dream Shard demand rises above supply the Auction House will start to get depleted and prices will rise. The skill here is watching the prices, logging on and posting your inventory at the right time in the right quantities depending on how fast you want to liquidate it.

You can sell a single Dream Shard at 30g and it will probably sell but it will take a week or more to find a buyer. If you post Dream Shards up for 10g they will sell in minutes. Once you get a feel for the prices you'll realize that prices are dependent not only on the current market but also on the amount of time you're willing to spend finding a buyer. This is dependent on too many variables, what day of the week it is, what time of the day, how many people are playing, if it's Super Bowl Sunday, etc. There is also no right answer when you ask what is a Dream Shard worth. I'm also not going to keep these price estimates updated as time goes by, since they will inevitably fluctuate.

Wow addon that shows auction prices