This will be no where near all the vendors in the game. But this list should be a helpful start for a few in some major cities.
Ironforge:
http://wow.allakhazam.com/db/mob.html?wmob=5109
http://wow.allakhazam.com/db/mob.html?wmob=5124
http://wow.allakhazam.com/db/mob.html?wmob=7978
Stormwind:
http://wow.allakhazam.com/db/mob.html?wmob=4981
Orgrimmar:
http://wow.allakhazam.com/db/mob.html?wmob=3342
http://wow.allakhazam.com/db/mob.html?wmob=3329
http://wow.allakhazam.com/db/mob.html?wmob=3368
Thunder Bluff:
http://wow.allakhazam.com/db/mob.html?wmob=3025
http://wow.allakhazam.com/db/mob.html?wmob=3017
Shattrath City:
http://wow.allakhazam.com/db/mob.html?wmob=19223
http://wow.allakhazam.com/db/mob.html?wmob=23263
http://wow.allakhazam.com/db/mob.html?wmob=19664