Screech

Pet Battle: [15-16] Un'Goro Crater; [22-23] Mount Hyjal

Vendor: Sylvia Hartshorn

Zone: Val'sharah

Faction: Dreamweavers - Revered

Cost: 500 (unlimited supply)

Pet Battle: [1-2] Undercity; [1-2] Tirisfal Glades; [3-6] Silverpine Forest; [12-13] Eastern Plaguelands; [22-23] Mount Hyjal

Drop: World Drop

Zone: Hillsbrad Foothills [7-30]

Approximate Drop Rate: 1 in 8,000

Vendor: Donni Anthania

Zone: Elwynn Forest

Cost: 40 (unlimited supply)

Vendor: World Vendors

Cost: 50 (unlimited supply)

Pet Battle: [23-25] The Jade Forest; [23-25] Valley of the Four Winds

Vendor: Breanni

Zone: Dalaran (Northrend)

Cost: 50 (unlimited supply)

Pet Battle: [1-2] Eversong Woods; [1-2] Elwynn Forest; [1-3] Silvermoon City; [7-8] Arathi Highlands; [20-21] Netherstorm

Pet Store 

Pet Battle: [3-4] Northern Barrens; [9-10] Southern Barrens

Pet Battle: [18-20] Blade's Edge Mountains

Vendor: Donni Anthania

Zone: Elwynn Forest

Cost: 40 (unlimited supply)

Drop: Talanji's Expedition Supplies

Zone: Nazmir

Approximate Drop Rate: Unknown

Drop: World Drop

Zone: Revendreth

Approximate Drop Rate: Unknown

Pet Battle: [24-25] Townlong Steppes; [24-25] Dread Wastes

World Event: Darkmoon Faire (first week of each month)

Vendor: Lhara

Zone: Darkmoon Island

Cost: 90 (unlimited supply)

Drop: Darkmoon Game Prize

Zone: Darkmoon Island

Approximate Drop Rate: 1 in 1,250

World Event: Darkmoon Faire (first week of each month)

Vendor: Lhara

Zone: Darkmoon Island

Cost: 90 (unlimited supply)

Drop: Darkmoon Game Prize

Zone: Darkmoon Island

Approximate Drop Rate: 1 in 2,000

Drop: Dart's Nest

Zone: Dustwallow Marsh [15-30]

Drop Rate: 1 in 1

Drop: Deviate Guardian, Deviate Ravager

Zone: Wailing Caverns [8-30]

Approximate Drop Rate: 1 in 555

Pet Battle: [15-16] Un'Goro Crater

Vendor: Freka Bloodaxe

Zone: Icecrown

Cost: 40 (unlimited supply)

Pet Battle: [25] Highmountain

Pet Battle: [25] Zaralek Cavern

World Event: Legion Invasion

Vendor: Captive Wyrmtongue

Cost: 150 (unlimited supply)