Making flasks in Cataclysm can be less profitable than you would expect. First, one of the most commonly used flasks, Flask of Titanic Strength, is the cheapest recipe to make at one point while leveling to 525. I never pay more than half the cost of the mats for these when I'm buying for my guild's strength-based raiders. I expect this to eventually change as fewer people are leveling alchemy, but that will probably happen around the same time that the price for Cataclysm mats finally goes as low as it's going to. One thing that'll never change is that this flask takes the cheapest herbs.
Speaking of herb cost, making a flask on live now will set you back 12 of two types of herbs and
9 6 Volatile Life. This will be changing in the next patch to be 8 Lifes and 8 of two types of herbs. Combine this with the recent change to the requirements for a guild to be able to make a cauldron, and the number of flasks being created will go through the roof. The number of flasks now needed is much more obtainable, which means that it's likely to be attempted. This will force the prices for these on the AH down in two ways: First, fewer people will need to buy them if their guild is making a bunch to get their cauldron. Second, even if the guild tries to recoup the price of their mats instead of giving them to raider for free, they will be increasing the amount available on the AH, which means more competition.
There's a much longer article I need to write about how to decide whether to get the cauldrons or buy flasks under cost on the AH, but it wouldn't fit into today's post. That said, if you want to make money on flasks, you need the 20% yield bonus from the specialization if you want to enjoy the same profit margins as your competition. Typically, the flasks that take more expensive herbs are the ones that are most likely to be profitable, as they are bad choices if you're trying to spam out the guild achievement or level your profession.
Ever since epic gems became transmutable in Wrath, this has become the simplest and one of the most profitable specialties. It's still very profitable in Cataclysm. The easy money for any alchemist is the daily cooldown, shared by Truegold and Living Elements. Specializing in transmutation will mean you get 20% more Truegold over time, and it means a chance of getting an extra proc of random volatiles. The thing with the volatiles is that while you can force the primary result to be whatever is worth the most, you can't force the random transmutation proc. Additionally, the total average number of volatiles generated by the procs for a transmutation specialist is not as easily derivable as procs for a single-creation item and has not been measured anywhere that I know of.
The less automatic money comes from transmuting gems. You can transmute rare gems from uncommon ones plus a couple of herbs. On any server where Elementium Ore is cheap, you can expect that the majority of rare gems will be available cheaper on the AH than their minimum price (assuming you cut and vendored the uncommon gems that go into the transmute for 9g apiece). Of course, the red gems are the exception. These, cut, provide all the core stats for the majority of every raid. They are prospected with the same frequency as all the other colors, but in addition, the uncommon red gems are used in manufacturing cheap enchanting mats. So if the price for Carnelians ever goes below about one-third of the price of a Greater Celestial, they get bought out by people who can craft and disenchant those weapons. All this adds up to these gems costing about two to five times as much as other colors of rare gems.
The other gem you can transmute is the Shadowspirit Diamond. You get two of these for three of each uncommon gem. Interestingly, while flasks in Wrath also provided two flasks per craft, the transmutation procs for the meta gem does not yield 20% but awards the same number of bonus gems as if it was making them one at a time. Flasks used to proc four, six, eight, or 10, and these proc three, four, or five, seemingly much more rarely. I'd estimate that this makes the transmutation bonus worth less than half: about 8% instead of 20%.
The hard cost for a single meta gem transmute is the value of the uncommon gems that go into it. If nobody on your server ever buys Nightstones for 90g when they're the JC daily, and the price for uncut reds isn't hovering around 30g because of the demand pressure I mentioned before, then the real cost is 162g for a pair, minus the procced gems. Of course, Nightstones really are worth about 80g when hundreds of jewelcrafters decide it's faster and cheaper to buy three off the AH than prospect a ton of ore to get them, and reds really are worth 30g when they can be made into the best agility and strength gems in the game as well as a commonly used enchanting material. Do the math before you transmute these.
Ah, potions. The sign of an excellent raider is someone who uses two of these each progression fight. Sadly, we were all so spoiled by the easy raid content in Wrath that I see the majority of people in raids not even using a flask or food. Part of this is the price of mats, but part of it is that people have grown used to easier content and don't factor consumables into "raid readiness." That said, schmucks like me still blow through potions at a staggering rate to compensate for my poor rotation and lack of raid awareness, causing premature death.
As with any alchemy market, simply see what they cost on the AH, and if the mats are lower after your 20% specialization yield, make them. You might also find some niche markets if there are people willing to pay for the weird potions. Also, while not strictly a potion, check out whether Deepstone Oil sells on your realm. I know on Drenden, nothing amuses the children more than getting on their enormous mount and freezing themselves right in front of a mailbox or auction house. I tolerate this only because I've probably made several thousand gold off these potions so far and have invested virtually no time into the market other than adding them to my APM sell list. That and, you know, not being able to stop them.
Maximize your profits with more advice from Gold Capped, plus the author's Call to Auction podcast. Do you have questions about selling, reselling and building your financial empire on the auction house? Basil is taking your questions at firstname.lastname@example.org.