1. first the guild must unlock the item through guild achievements and/or other feats.
2. secondly, you must have the correct guild reputation.
3. lastly, you must have enough gold (i guess?).
here's the full blue quote:
"The guild rewards you guys are seeing in game are not hooked up yet. Guild rewards have 3 requirements that must be be met before you can use them. First and foremost, they must be unlocked via a guild achievement. Let's just say, that for example, you need to complete the new guild achievement "We are Legendary" in order to unlock the Dark Phoenix. That achievement requires the guild to gain access to all 6 legendary weapons currently available in the game. (note that all guild achievements start on Cataclysm launch, so anything you have now will not matter, it must be done with your guild after launch)
So, let's say that your guild get's this achievement and thereby unlocks the Dark Phoenix on the guild vendor. At this point anyone in the guild can see the item on the vendor, but they will need a specific amount of guild faction to be able to purchase it. In this case, let's say exalted. Now, once you have the guild faction, you can purchase the item for its gold price. (prices will vary based on the reward)
I am using the Dark Phoenix and the We are Legendary guild achievement as examples here but you should get the idea. Don't worry, we wont be handing out all the goodies so easily. =)" - Mumper
so hold your squees and leaps of joy for the two new companions, because it looks as if it won't be easy street for collectors to obtain them. which achievements, feats, or other actions guilds will need to complete in order to unlock the pets... there's no information on that yet. currently, the guild achievements on the beta realms do not have any rewards listed for completing them.
as a guild leader, i'm not quite sure how i feel about this system. as a pet collector, i'm quite annoyed. blizzard has implemented, yet again, pets that favor one side of the coin more than the other, rather than finding a balance and a compromise.
i can foresee this system leading to a host of problems such as collectors who cannot get into a guild will be cut off from obtaining the companions. please don't tell me, 'just make a guild with a couple of randoms or a few friends!' since it is unclear just what will need to be done in order to unlock the guild vendor items, a "few friends" may not be enough. most of the achievements currently listed require a "guild group." ("A guild group/raid is 4/5, 8/10, 12/15 or 20/25 members of the group/raid being guild members." - Mumper) and since it was already stated that they do not want to "hand out all the goodies too easily," who knows just which achievement will be necessary. a small group of say 4 collector friends in a guild just will not cut it if they need to complete a raiding achievement.
this system of "unlocking" and "reputation" will make the guild vanity pets tougher to obtain, and in guilds where the interest is divided between raiding, pvp, and achievements/completion, there will definitely be some drama over the direction of the guild. will this system divide a guild? one side will obviously want to focus more on unlocking one thing while the other side will want to concentrate on other things.
these rewards and guild achievements are still in the early stages, so we'll hopefully see some favorable changes in the near future. i haven't formulated a concrete opinion on this yet, but so far i can definitely feel there will be some (negative) issues connected with the guild vendor vanity items.
