Shimmering Wyrmling

Source
Shimmering Wyrmling is sold by the Argent Tournament vendor for Alliance players, or  for Horde players, in Icecrown for.

This item can also be found inside Satchel of Exotic Mysteries.

It also has a chance to be listed on the Black Market Auction House by Breanni, for the opening bid of.

Pet Journal
This extremely rare species of mana wyrm is prized for its unique coloration and even temperament.