Iceblade Arrows are the most popular ammo in the game now. The most accessible (and thus popular) weapons for hunters seem to be bows or crossbows. Despite my good buddy Brian's refusal to use them, they remain the lion's share of the epic ammo market. The bullet equivalent, Shatter Rounds, are also sold, but in much lower quantity.
Gnomish engineers (the specialization, not the race) can buy Plans: Iceblade Arrow from Alchemist Finkelstein in the Icecrown Citadel for the cost of one Primordial Saronite. Goblin specs can get Plans: Shatter Rounds. That's a pretty hefty price to get into the market; however, it pays off if you can make any amount of profits. Bear in mind, you need to be honored with the Ashen Verdict. Check out this Insider Trader from last December for the whole story.
Once you can make your ammo, it's just a matter of selling it. Hunters tend to stock up on these, but there's a definite demand surge on Tuesdays before raids (like many raiding consumables). The demand is pretty high all the time, though, so keeping your stock listed all the time will increase your market size. Pricing your ammo is a little tricky, however. Assuming you're not the only person selling these, you will need to decide on a strategy and stick to it. The mats for the arrows are two Crystallized Shadow, or two Crystallized Earth for the bullets. Eternal Shadow and Earth prices are typically fairly low. On my server, shadow can be gotten for 3.5g pretty reliably, which makes a stack of 1,000 arrows cost 70 silver to make. These stacks often sell for close to 10 gold.
You have to decide whether to undercut by a slight amount and share the volume at higher profits, or undercut heavily and get a larger slice of the pie at a lower profit margin. Bear in mind that lower prices on the AH will increase the size of the pie, too. Arrows are not "fixed demand" commodities. In fact, there are no fixed demand commodities in the game. People will never just buy something, no matter the price. Whether high volume with lower profitability is more money in the end than lower volume with higher profitability is something you have to calculate yourself.
Now you may ask yourself why I'm not advocating multiple stack sizes here. The reason for that is that no hunters ever want to buy less than a full stack of ammo. If they ever do purchase that, it's by accident, and if you sell small stacks of ammo for the same price as a full stack, there's a special place in hell for you. I'm not saying that hunters don't make mistakes and not double-check the three-point font number below the icon on the 10th stack they buy -- but I am saying that if you are the person standing there ready to take 10g from a well intentioned client, you are a failure. Karma will work it all out in the end, and in the meantime, all you've done is ruin someone's day (and possibly raid night).
Cute, lovable and pointless. It's the perfect storm of economic success. Engineers can make several sellable non-combat pets. The ones that are in the highest demand are the recently made BoE pets from Gnomeregan, and I went over the crafting mats and pricing schemes for these in another post.
Additionally, there are a bunch of other pets engineers can sell, some of which are very hard to learn and might be worth a lot of money if you can keep a small stock on the AH at all times. The schematics for these are impossible to farm, so add them to your snatch list and buy it if they're ever on the AH. These usually sell very well for a nice profit margin.
In addition the the ability to make a few things for the AH, engineers can make themselves a Zapthrottle Mote Extractor
, which allows you to farm elementals from gas clouds (which you can see on your map if you have the extractor in your inventory). This is a minor benefit, but assuming you spend any time outside the auction house, it's a benefit.
Random items needed by others
Last but not least, we have this list of random items that are occasionally needed by others.
And the following items are needed for quests:
There you have it! Combine some or all of these markets, and you might just make more than you'd get spending the time farming dailies.
Being an auctioneer is like being able to print money (or gold, as it were). Wait, that doesn't make sense ... You can print on gold, but you can't print gold. That would be closer to transmutation? I can transmute titanium, but that's only worth it if the price of saronite is low enough to justify the time spent making it. I need some sort of analogy here. ... Whatever, I'll figure it out later. Making gold? Every week, Gold Capped will teach you the tricks of the trade, from setting up your auction addons and user interface, to cross-faction arbitrage, to learning how to use your trade skills.