Shop Smart, Shop Pet...Smart

If you complete this Achievement you will get the Reeking Pet Carrier (a skunk). The Achievement will be active from patch 3.0. You can collect 50 vanity pets before Wrath of the Lich King. I have listed most of them below. Good luck!

Vendor Items (Both Factions):

1. Blue Dragonhawk Hatchling ( Netherstorm )
2. 
   
3. Brown Rabbit Crate ( Netherstorm )
4. 
   
5. Cat Carrier (Siamese) ( Netherstorm )
6. 
   
7. Mana Wyrmling ( Netherstorm )
8. 
   
9. Red Moth Egg ( Netherstorm )
10. 
    
11. Cokroach ( Netherstorm )
12. 
    
13. Crimson Snake ( Netherstorm )
14. 
    
15. Parrot Cage (Cokatiel) ( Stranglethorn Vale )
16. 
    
17. Parrot Cage (Senegal) ( Stranglethorn Vale )
18. 
    
19. Ancona Chicken ( Thousand Needles )
20. 
    

Vendor Items (Alliance):

1. Rabbit Crate (Snowshoe) ( Dun Morogh )
2. 
   
3. Cat Carrier (Bombay) ( Elwynn Forest )
4. 
   
5. Cat Carrier (Cornish Rex) ( Elwynn Forest )
6. 
   
7. Cat Carrier (Orange Tabby) ( Elwynn Forest )
8. 
   
9. Cat Carrier (Silver Tabby) ( Elwynn Forest )
10. 
    
11. Cat Carrier (White Kitten) ( Stormwind City, Rare Vendor )
12. 
    
13. Great Horned Owl ( Teldrassil )
14. 
    
15. Hawk Owl ( Teldrassil )
16. 
    
17. Blue Moth Egg ( The Exodar )
18. 
    
19. White Moth Egg ( The Exodar )
20. 
    
21. Yellow Moth Egg ( The Exodar )
22. 
    

Vendor Items (Horde):

1. Golden Dragonhawk Hatchling ( Eversong Woods )
2. 
   
3. Red Dragonhawk Hatchling ( Eversong Woods )
4. 
   
5. Silver Dragonhawk Hatchling ( Eversong Woods )
6. 
   
7. Black Kingsnake ( Orgrimmar )
8. 
   
9. Brown Snake ( Orgrimmar )
10. 
    
11. Prairie Dog Whistle ( Thunder Bluff )
12. 
    

Crafts:

1. Mechanical Squirrel Box ( Engineering 75 )
2. 
   
3. Tranquil Mechanical Yeti ( Engineering 250 )
4. 
   
5. Lifelike Mechanical Toad ( Engineering 265 )
6. 
   
7. Lil' Smoky ( Gnomish Engineering 205, BoP )
8. 
   
9. Pet Bombling ( Goblin Engineering 205, BoP )
10. 
    

Normal Quest Reward Items:

1. Sprite Darter Egg ( Feralas, Alliance Only )
2. 
   
3. Chicken Egg ( Westfall, Alliance Only )
4. 
   
5. Mechanical Chicken ( Stranglethorn Vale )
6. 
   
7. Miniwing ( Terokkar Forest )
8. 
   
9. Smolderweb Carrier ( Blackrock Spire )
10. 
    
11. Worg Carrier ( Blackrock Spire )
12. 
    

Fishing Daily Quest Reward Items:

1. Chuck's Bucket ( Daily Fishing Reward )
2. 
   
3. Muckbreath's Bucket ( Daily Fishing Reward )
4. 
   
5. Snarly's Bucket ( Daily Fishing Reward )
6. 
   
7. Toothy's Bucket ( Daily Fishing Reward )
8. 
   

Drops:

1. Azure Whelpling ( Azshara )
2. 
   
3. Captured Firefly ( Zangarmarsh )
4. 
   
5. Cat Carrier (Black Tabby) ( Silverpine Forest, Horde only )
6. 
   
7. Dark Whelpling ( Dustwallow Marsh )
8. 
   
9. Disgusting Oozeling ( Felwood )
10. 
    
11. Parrot Cage (Green Wing Macaw) ( The Deadmines )
12. 
    
13. Parrot Cage (Hyacinth Macaw) ( Stranglethorn Vale )
14. 
    
15. Phoenix Hatchling ( Magister's Terrace )
16. 
    
17. Tiny Crimson Whelpling ( Wetlands )
18. 
    
19. Tiny Emerald Whelpling ( Swamp of Sorrows )
20. 
    

Special kind of Drops:

1. Mojo ( Zul'Aman, Amani Hex Stick)
2. 
   
3. Magical Crawdad Box ( Fishing, Mr. Pinchy )
4. 
   

Reputation Rewards:

1. Nether Ray Fry ( Skyguard )
2. 
   
3. Tiny Sporebat ( Sporeggar )
4. 
   

Special Event Items:

1. Wolpertinger's Tankard ( Brewfest )
2. 
   
3. Egbert's Egg ( Children's Week )
4. 
   
5. Elekk Training Collar ( Children's Week )
6. 
   
7. Piglet's Collar ( Children's Week )
8. 
   
9. Rat Cage ( Children's Week )
10. 
    
11. Sleepy Willy ( Children's Week )
12. 
    
13. Turtle Box ( Children's Week )
14. 
    
15. A Jubling's Tiny Home ( Darkmoon Faire )
16. 
    
17. Tree Frog Box ( Darkmoon Faire )
18. 
    
19. Wood Frog Box ( Darkmoon Faire )
20. 
    
21. Sinister Squashling ( Hallow's End )
22. 
    
23. Truesilver Shafted Arrow ( Love is in the Air )
24. 
    
25. Scorched Stone ( Midsummer Fire Festival )
26. 
    
27. Captured Flame ( Midsummer Fire Festival )
28. 
    
29. Green Helper Box ( Winter Veil )
30. 
    
31. Jingling Bell ( Winter Veil )
32. 
    
33. Red Helper Box ( Winter Veil )
34. 
    
35. Snowman Kit ( Winter Veil )
36. 
    

Exclusive:

1. Banana Charm ( TCG )
2. 
   
3. Blue Murloc Egg ( Blizzcon )
4. 
   
5. Clockwork Rocket Bot ( Winter Veil, Only 2007 )
6. 
   
7. Competitor's Souvenir ( Olympics )
8. 
   
9. Diablo Stone ( CE )
10. 
    
11. Dragon Kite ( TCG )
12. 
    
13. Fortune Coin ( Worldwide Invitational )
14. 
    
15. Gold Medallion ( Olympics )
16. 
    
17. Golden Pig Coin ( Promotional )
18. 
    
19. Green Dragon Orb ( Promotional )
20. 
    
21. Hippogryph Hatchling ( TCG )
22. 
    
23. Lurky's Egg ( CE )
24. 
    
25. Netherwhelp's Collar ( CE )
26. 
    
27. Panda Collar ( CE )
28. 
    
29. Pink Murloc Egg ( Contest )
30. 
    
31. Polar Bear Collar ( Promotional )
32. 
    
33. Red Dragon Orb ( Promotional )
34. 
    
35. Rocket Chicken ( TCG )
36. 
    
37. Silver Pig Coin ( Promotional )
38. 
    
39. Soul-Trader Beacon ( TCG )
40. 
    
41. Tyrael's Hilt ( Worldwide Invitational )
42. 
    
43. Zergling Leash ( CE )
44. 
    

Regards,

Immortares
(EU - Twisting Nether - Alliance - Aeternitas)

Alright you Primitive Screwheads, listen up! You see this? This... is my boomstick! The twelve-gauge double-barreled Remington. S-Mart's top of the line. You can find this in the sporting goods department. That's right, this sweet baby was made in Grand Rapids, Michigan. Retails for about a hundred and nine, ninety five. It's got a walnut stock, cobalt blue steel, and a hair trigger. That's right. Shop smart. Shop S-Mart. YOU GOT THAT?

EDIT: Quoted from Bruce Campbell in part of the Evil Dead movie series. —Arideni

I didn't notice the above list before I started making one of my own in preparation of tomorrow's patch. Here are all of the pets that I know of, in some sorts of an order. Good luck achieving this!

Pets List

Vendor - Alliance Cities
Elwynn
1. Cat Carrier (Bombay)
2. Cat Carrier (Cornish Rex)
3. Cat Carrier (Orange Tabby)
4. Cat Carrier (Silver Tabby)

Dun Morogh
5. Rabbit Crate (Snowshoe)

Darnassus
6. Great Horned Owl
7. Hawk Owl

Exodar
8. Blue Moth Egg
9. White Moth Egg
10. Yellow Moth Egg

Stormwind
11. Cat Carrier (White Kitten)

Vendor - Horde Cities
Orgrimmar
12. Black Kingsnake
13. Brown Snake
14. Crimson Snake

Undercity
15. Coсkroach

Thunder Bluff
16. Prairie Dog Whistle

Eversong Woods
17. Golden Dragonhawk Hatchling
18. Red Dragonhawk Hatchling
19. Silver Dragonhawk Hatchling

Vendor - Neutral
Thousand Needles (Race Track)
20. Ancona Chicken

Stormspire
21. Blue Dragonhawk Hatchling
22. Brown Rabbit Crate
23. Cat Carrier (Siamese)
24. Mana Wyrmling
25. Parrot Cage (Senegal)
26. Red Moth Egg

Booty Bay
27. Parrot Cage (Coсkatiel)

Darkmoon Faire
28. Wood Frog Box
29. Tree Frog Box

Easy Obtainable
30. A Jubling's Tiny Home [Darkmoon Faire]
31. Chicken Egg [Alliance Quest/Westfall - Sorta Horde Obtainable]
32. Mechanical Chicken [Chicken Escort Quests]
33. Miniwing [Quest/Terrokar]
34. Smolderweb Carrier [Quest/Burning Steppes - LBRS]
35. Worg Carrier [Quest/Burning Steppes - LBRS]
36. Mechanical Squirrel Box [Engineering]
37. Lifelike Mechanical Toad [Engineering]
38. Tranquil Mechanical Yeti [Engineering]
39. Sprite Darter Egg [Alliance Quest/Feralas - ALLIANCE ONLY]
40. Parrot Cage (Green Wing Macaw) [Drop - Deadmines]

Sorta Obtainable/Seasonal
41. Wolpertinger's Tankard [Brewfest]
42. Green Helper Box [Winter Veil]
43. Red Helper Box [Winter Veil]
44. Jingling Bell [Winter Veil]
45. Snowman Kit [Winter Veil]
46. Truesilver Shafted Arrow [Love is in the Air]
47. Captured Flame [Midsummer Festival]

Reputation
48. Nether Ray Fry [Skyguard]
49. Tiny Sporebat [Sporeggar]

Fishing Daily
50. Chuck's Bucket [Crocolisks in the City]
51. Muckbreath's Bucket [Crocolisks in the City]
52. Snarly's Bucket [Crocolisks in the City]
53. Toothy's Bucket [Crocolisks in the City]

Low Drops
54. Cat Carrier (Black Tabby) [Drop - Silverpine/Alterac - Horde Only, Tradeable to Alliance]
55. Azure Whelp [Azshara]
56. Dark Whelpling [Dustwallow Marsh/Badlands]
57. Tiny Crimson Whelpling [Wetlands]
58. Tiny Emerald Whelpling [Swamp of Sorrows]
59. Captured Firefly [Zangarmarsh]
60. Disgusting Oozeling [51+ Oozes]
61. Parrot Cage (Hyacinth Macaw) [Stranglethorn Vale]

Boss Drops
62. Pheonix Hatchling [MgT Kael'thas, Normal/Heroic]
63. Sinister Squashling [Hollow's End]
64. Scorched Stone [Midsummer Festival]

Children's Week
65. Egbert's Egg [Outlands]
66. Elekk Training Collar [Outlands]
67. Sleepy Willy [Outlands]
68. Piglet's Collar [Azeroth]
69. Rat Cage [Azeroth]
70. Turtle Box [Azeroth]

Fishing
71. Magical Crawdad Box [Mr. Pinchy]

Raid
72. Mojo [Zul'Aman]

Engineering ONLY
73. Lil' Smoky [Gnomish]
74. Pet Bombling [Goblin]

No Longer Obtainable/Collector's
75. Clockwork Rocket Bot [Winter Veil '07]
76. Gold Medallion [Olympics '08 Event]
77. Netherwhelp's Collar [tBC CE]
78. Diablo Stone [Original CE]
79. Panda Collar [Original CE]
80. Zergling Leash [Original CE]
81. Blue Murloc Egg [Blizzcon '05]
82. Tyrael's Hilt [WWI '08]

Card Game
83. Dragon Kite [March of the Legion]
84. Hippogryph Hatchling [Heroes of Azeroth]
85. Banana Charm [Dark Portal]
86. Rocket Chicken [March of the Legion]
87. Soul-Trader Beacon [Hunt for Illidan]

WRATH OF THE LICH KING
88. Baby Shark [Lake Wintergrasp Vendor]
89. Proto-Drake Whelp [The Oracles - Revered]
90. Ghostly Skull [Vendor - Dalaran Sewers]
91. Giant Sewer Rat [Fished - Dalaran Sewers]
92. Penguin Egg [Blizzard Account]
93. Frosty [WotLK CE]
94. Nurtured Penguin Egg [The Kalu'ak - Exalted]

And the achievement awards:
95. Reeking Pet Carrier

Never Obtainable on US Realms
96. Lurky's Egg [Europe tBC CE]
97. Pink Murloc Egg [Europe Contest]
98. Fortune Coin [WWI '07, Asia]
99. Competitor's Souvenir [Olympics '08 Event, China]
100. Red Dragon Orb [China Promo]
101. Green Dragon Orb [China Promo]
102. Silver Pig Coin [China Promo]
103. Polar Bear Collar [China Promo]
104. Golden Pig Coin [China Promo]

Edit (1): Go go overzealous censors.
Edit (2): Slight edits to the list.