Commodities

Commodities are essentially something tangible people want. In Warcraft, these could be gems, ore, glyphs herbs, enchanting mats, and so forth.

Controlling one of these markets is nearly impossible. No matter how many stacks of ore I buy, more can be farmed. Thus, if you are attempting to invade such a market...one must move...cautiously. You can manage to control one in the short term, but never in the long term.

A bad example of a short term market would be hypnotic dust. There's an endless supply and most enchants that people demand do not require massive amounts of it. Prime glyphs are likewise dangerous to invest in too heavily...since they are being removed.

A better choice would be maelstrom crystals. With LFR and normal raiding, many people don't do heroics anymore and the amount of these entering the game is greatly lessened. .On my own server there's less than 100 in the auction house, averaging around 200 gold each. If I bought the entire supply for 20,000 gold...and put them all up for 800...what would happen? Certain enchants that require them would spike up in value—if your pockets were really deep you could buy all the premade versions of every maelstrom crystal enchant and spike those as well. This is generally what happens before a big patch day with new raiding content. The same could be true of red gems or whatever else.

As a side note, is this against the eula? It is definitely not. This post talks about it. Blizzard operates in a perfect capitalist economy. http://us.battle.net/wow/en/forum/topic/4081812872

Let's look at other potential markets. The first to consider is new characters. New characters often will level gather skills and then switch to production skills at max level. If your corner the markets on materials from say 30 to 80, you can really stick it to them. Especially valuable are the 50 to 60 enchanting materials that are use on bind on account weapons and armor. Also, burning crusade materials and lich king are in much lower supplies and demand higher prices in the AH. The speed in which someone levels through TBC these days makes fel iron and the herbs of that expansion very easy to monopolize. These materials are often the beaten path for level 85's and their pandarians will surely need assistance (as do most death knights). Low level herbs can be used to craft high level glyphs, so these are another good choice. Cloth will be highly sough after as well, especially to create bags for all the new monks. One must again be patient and cautious about which markets are worth invading.

It is interesting to note that maelstrom crystals won't be highly sought after, after Cata is over—it is the dust and essences that people will need in the long term to level enchanting. If Blizzard maintains their model, enchanting will be leveled from 425 to 500 on cata mats, and new recipes will help new enchanters get to 525. This type of speculation means it will pay off to have a large stockpile of dusts and essences. Wrath was different because you could shatter abyss crystals into dust and essences....maelstroms only are turned into shards. This matches the TBC model, and if you investigate it, both crystals and shards from that expansion are nearly worthless.

Once you are an established gold guru, cornering a market is a risk you can potentially take. I did this with flasks right before Ulduar to great success. During the end of wrath, I gambled glyphs would increase in value immensely as gold became more plentiful and that people will still want them in the future. I spent almost 50k (almost 20 percent of my wealth) buying up 8 gold icethorn and would crank glyphs out when they took one ink each out for 1-2 gold and in turn resold them for between 200 and 275 gold each—a massive profit margin when I had 16,000 glyphs at my height.. But, the goblin must be wary...for grasping the wrong market can be like trying to hold onto lightening.