There is a problem with players who like to post huge amounts of items by one piece, for example 300 lots of netherweave cloth, 1 item each. I think this has a negative effect on the auction work and the server performance. In some cases it really makes sense to post items individually. For example high price, rare items which not use in huge amounts (Shadowcloth, Spellcloth, Primal might, Skyfire Diamond etc.) But most of items could be post by max available of stack.
Blizzard tried some fix that problem. Before they had rework auction system:
To address some issues related to the Auction House, we’re reconsidering how deposits—the refundable fees you pay to list your auctions—are calculated. This fee is based on the item’s vendor price, and for profession materials in particular, vendors offer very low prices, so these mats have a low deposit cost. Deposits are substantial on items such as BoE uncommon gear, gems, and so forth, but not trade skill materials (trade goods such as cloth, ore, leather, etc.).
One thing we’ve identified as particularly troublesome is a large volume of trade skill materials being auctioned off in stacks of 1. Some addons make posting quantities of this size trivial to do, resulting in dozens, if not hundreds, of pages of auctions for a single item. As we looked at ways to change this behavior and improve the overall Auction House experience, we found that we prefer to avoid inflexible solutions such as caps on the number of listings a player can make, or increased minimum stack counts, which might interfere with many players' common gameplay habits.
Our current plan is to increase the deposit cost of some profession materials on a per-stack basis, which should provide incentive for players to post items in larger stacks.
Here's an example:
• Let’s say that a player is trying to sell 200 Tidespray Linen for 10g (gold) each. Today, each item has the normal deposit cost of 1c (copper), with a 1s (silver) minimum deposit, so 1 auction of 200 linen requires a deposit of 1s, and 200 auctions of 1 linen each adds up to a total deposit of 2g.
• Now imagine an additional 20% deposit added to the listing fee per auction. With an asking price of 10g each, that raises the deposit by 2g per stack. In the case of 1 stack of 200 linen, the total buyout price is 2000g, and the new deposit is 2g1s. In the case of 200 individual stacks, the new deposit of an additional 2g per stack brings the total deposit up to 402g.
In either case, the deposit is returned to the seller if the item sells. Successful auctions aren’t affected by this change.
Our goal is to give players some forewarning on this change, and to gather feedback. We’re putting together a list of the items that would be affected by this deposit change, which we expect to be limited to high-quantity trade goods. Furthermore, we’re deploying the change to the PTR first, so that addon authors can work through the change while we test it thoroughly.
This change will likely be a temporary measure, as we’re also working to broadly improve the default Auction House in the future. It’s clear to us that many players use addons because they find the default Auction House interface inadequate. A temporary change to deposit fees will help with this in the short term, and we’ll continue to work on overall improvements to the Auction House for a future patch.
When I see all those auctions of single items I think the player does it on purpose.
It's as if selling hundreds of objects of the same type amuses him in some way, this is just an opinion, I'm not blaming anyone. I prefer to specify it in case anyone feels annoyed.
If, on the other hand, behind this way of selling there is a precise purpose that allows them to accumulate more gold, well, good for them then.
As for rare items at high prices, they are actually a bit high but if they are it's because there are players who buy at those prices and by buying at those prices they do nothing but incentivize those who sell to continue in this way.
Your suggestions might be helpful, let's see if any of the developers say anything about it.