You all -know- you want it.
With the guild closing on level 20, it may very well be worth looking into getting everyone involved in gathering all the needed materials for the super-sized cauldron. While it may seem very daunting as individuals, it's certainly possible to achieve given the concerted effort of as a large group such as Apotheosis. We're already well over a third there! This would also possibly open the door for the guild to provide flasks for the raid, even before we get the achievement completed.
Currently we need approximately 1700 flasks to reach our goal. Divided evenly among the most commonly used flasks (Which also happen to be the ones used for cauldrons), that's 430 of each. Assuming we use elixer masters, which we should, with an assumed proc-rate of 10%, we'll need to make about 400 of each flask. But consider this: How many flasks do we use per raid? 3 or 4 each. (Except Irloki, but he doesn't count.) Per raid, that's 75-100 flasks per raid day. That's 250-300 per week! If we start working on this as a guild, and stop buying flasks out of the Auction House, we'll get there pretty quickly. It'll only take us a little over one months worth of flasks to get the achievement. And then you can stop carrying around flasks in your bags. Who doesn't want that?!
Now for the nitty-gritty. 400 of each flask. 8 each of 3 materials (not counting bottles). That's 320 stacks of Whiptail, Azshara's Veil, Cinderbloom, and Twilight Jasmine. And a whopping 64 stacks of Volatile Life (Remember that one stacks up to 200). We have a fairly large number of Herbalists in the guild. We also have a fairly large amount of gold hoarders and whatnot. Everyone needs at least 3 flasks per raid. Everyone. That's what you plan on unless you like mooching off of others, or plan to not get caught by Xirony (which is fairly unlikely). If you're going to be buying them anyway, just buy mats and approach one of the Alchemists in the guild. I'm one, Hankisback is another. Winkatink, Nexvotum, Payload, Wilicia, and even Shifterror are also Alchemists. And that's just the raiders, many of us have alts, and some of those are also bound to be Alchemists. Hopefully the Elixer Masters among us will speak up and offer their services.
If you would like to contribute to the guild, be it herbs, food, volatile elements, gems, enchanting materials, metal and ore, or just gold, you should talk to an officer (keep in mind, I am -not- an officer). I've been informed that contributions to the guild are always welcome and noticed. Step up and be part of the experience.