is sold by  <Alchemy Supplies> in Gadgetzan.
When the cooldown was removed, the supply was greatly increased driving down prices significantly (from 15-20 gold, per bar, to 5-10 gold, for example). The demand for the ingredients skyrocketed resulting in an equal increase in price and decrease in supply, for especially the rare Arcane Crystals.
This skill was a major income for alchemists (example: one bar per day at 15-20 gold with the materials costing 3-5 gold resulting in a daily income of 10-15 gold, with no effort at all). The dramatic shift in the supply and demand somewhat crippled this steady income. When the market has settled down and all alchemists have sold all the cheap bars they could make from buying the ingredients at the pre-2.4 low prices, the price might go up again since the material cost for one bar has been revved up so much.
The removal of the cooldown could also create a scenario where alchemists make more gold just selling their transmuting services, since the required materials are too expensive to make a decent profit on constantly having bars at the Auction House.
- Patch 2.4.0 (25-Mar-2008): Cooldown removed.
Old was 23 hours.