The golden period of this scheme has aged somewhat, but with patch 4.0.3a the drop rate of Savory Deviate Delight and the Elixir of Giant Growth recipes has increased dramatically. These are zone drops in North Barrens (and presumably South Barrens), which means any given mob in those zones has a chance to drop them. Given the nature of Horde questing through the Barrens pretty regularly, the Horde market for these two now-common drops is probably low enough on your server that you would be better off selling Wool Cloth. But as for the Alliance...?
If you have a second account and/or toons on both factions of the same server, you can probably make a decent margin buying the patterns Horde-side and then selling on the Alliance AH. The alternative may be a little bit easier in this case: farm it yourself.
The toon I used was my level 71 hunter, who is otherwise chilling out in Dalaran in the 20 minute DPS queues. Now while there are technically a lot of areas where you can farm mobs for these two drops, I am recommending Fray Island in SE North Barrens. Mobs you are going for are the Southsea pirates. The hunter is perfect for this because he has a 38% movement speed with Cheetah Aspect + talents, can track humanoids, will one-shot the mobs with ranged attacks, and has Dalaran as his hearth. That last part is actually the most important.
Starting from Dalaran, you can take the Cavern of Time portal to Tanaris, mount up, and then trek straight across to the FP south of Gadgetzan. From here it is a quick FP up to the besieged Alliance town of Northwatch Hold. From there, it is a short ride to Fray Island. If you don't have the Northwatch Hold FP, you can either take one to Ratchet and head south, or go to Theramore and head north along the coast.
The reason I like Fray Island is A) it is out of the way* and yet easy to get to, B) the humanoid mobs respawn very quickly, C) each mob gives you a handful of rep with all four goblin factions (if you're into that sort of thing), and D) I am 100% positive both recipes drop here. I farmed the harpies up at Dry Hills for about ten minutes and got nothing - while it could be bad luck, if I am going to get down and dirty farmin' I want sure-things only. In my experience on Fray Island, the ratio was 2:5 on Savory Deviate Delight vs Giant Growth Potion drops. Random loot is still random of course.
The Deviate recipe will sell for more because every toon is capable of cooking, whereas only Alchemists can learn the Giant Growth elixir. It is probably a good idea to snatch up all the reasonable Deviate Fish that may be on the AH - with the increased availability of these two recipes (both of which require Deviate fish), you can expect the demand for Deviate fish to increase.
As a final note: don't just vendor all the greens and other drops you get from slaughtering the level ~15 mobs. You can usually push sales by listing every green at 5g minimum (undercutting identical auctions if necessary) with the weapons going for 10g
*Edit: There is actually a quest in Ratchet that sends Alliance/Horde toons to this island, so you may actually see traffic coming from that direction. It is still pretty out of the way.