The easiest place to get this Alterac Swiss is just to buy it from Inn Keeper Anderson in southshore Inn.

Alliance has tons of places to buy it.

Horde needs to buy it from the innkeeper in either Thousand Needles or Arathi.

I believe the vendors sell them 5 for 40 silver. Of course, by this time you should be honored in at least one city, so you should be able to get 5 for 36 silver. It's really not that much, only 1.6 gold or 1.44 gold if you're honored. Giant Eggs are kind of annoying to get though.

You can buy Alterac Swiss for 36 silver for a 5 stack. :) From the Innkeeper in Shadowprey Village in Desolace.

Maybe the Trias Cheese Shop in Stormwind sells some. =)

You can buy Alterac Swiss from Innkeeper Trelayne in Darkshire - instead of Chef Grual (same town), who does not sell anything now.

Got mine from inkeeper anderson for 36s per (5) in Southshore.

For the alliance also the cook Craig Nollward sells Alterac Swiss.

Just get the Alterac Swiss from the Innkeeper in Thunder Bluff.

=D

Cheeseshop by flight point, Elaine Trias is the vendor

You can get this for the cooking quest (at 225 cooking) from the caverns of time provisioner. I've just been to see him on my 56 pally, no hostiles on the way. Means that all 3 of the things you need to collect for the quest can be collected in Tanaris.

For Horde go to the innkeeper in Hammerfall at Arathi Highlands. 73,32

The cheese can also be bought on the boat from Booty Bay to Rachet.

Elaine Trias, Mistress of Cheese, at Stormwind City has unlimited supplies.  I checked today as path 2.3, it is UNLIMITED supplies.  Thottbot is wrong about this. 

I use my alt to buy the cheese for me for cook 225+ skill quest.

If you're trying to be efficient, the bartender (not innkeeper) in the Wildhammer Stronghold in the Hinterlands sells this.

This is convenient because the wildkin in the Hinterlands are one of the better sources for Giant Eggs, and if you're a skinner or miner there is good leather/metal to be had in the area as well.

OMG....INNKEEPER AT ARATHI HIGHLANDS. You'll have to scroll a few pages down, but it is infact there.

The cheese shop in Stormwind has it.

Apparently the Thunder Bluff Inn sells it. 

Innkeeper Pala in Thunder Bluff has it for 36 silver

Note that there is no vendor on the new zep to/from borean tundra, make sure you get in a old world zep and go downstairs.

I bought it from the machine in the Zepplin.

Tavernkeep Smitts in Duskwood is not even an NPC that sells anything, so he should not be on the list to purchase it from. I got mine from Innkeeper Treylane standing right next to Smitts in Duskwood.

Don't bother trying to find this at the boat from Ratchet to STV ... there is no vending machines there >_<

look for bartender @ Aerie Peak