At the start of cataclysm; there was an absolute flood of flasks; with them being sold below cost so that guilds could level for their cauldrons. Even I fell for this; making far too many flasks that were simply not needed at that time.
However, elixirs were still significantly cheaper; and while two elixirs had one offensive one defensive bonus; they were still a solid option. As such they sold well; and profitably.
This means that if any class of item is needed for new guild achievements, let the seller beware. They again are likely to be sold below cost.
Speculatively I think potions will be in large demand. I suspect that many healers will be reaching for some form of mana regeneration potions during MoP; Mana regeneration is designed to be tight this expansion. Instant mana for dungeons; and mana over 12 second potions for raids.
It looks like alchemists will (again) learn the majority of recipees randomly after creating stuff, with new recipes being made available as you level up. It might be worth creating a few potions or elixirs every 25 skill points or so, and rotating between potions, elixirs and transmutes; and seeing what recipes 'pop' up.
Also be aware that for this expansion; simply transmuting gems to red may not always be the best option. I have read that the importance of many secondary stats have been significantly increased I am already reading a few healing blogs recommend spirit over intellect. Watch the auction house and transmute what you can; and of those recipes; transmute the most profitable items. Keep an eye on class specific sites (or elitist jerk forums) for what gem colours are being recommended.
Make sure you have a specialisation (potions; flasks/elixirs; tranmutes); and concentrate on those recipes. You may find that it better to concentrate on pots and elixirs early. Flasks were created in too large a number early as guilds were trying to grind out their flask achievements.
Regardless of your specialisation; make sure you find your profitable transmute and do it every day. I am uncertain of whether you will get to choose the elemental transmute the same way we did in Cataclysm.
As I have mentioned ad nauseum; read Kaliope's website for MoP changes. I have not been bribed. For yet another expansion, Kaliope has some of the best Beta investigative reporting of any blog I can think of.
(PS. now that the patch has dropped and the rush is no longer entirely there, the next post will be my Monday morning)
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