Board Thread:Dragon City Mobile/@comment-25129101-20130907002824/@comment-10090661-20130908020855

Sheena, if you can't get the Kindy or Dragonarium, you have two options -- keep it in the Hatchery until you can afford the Habitat, or sell it and breed again later. The former is a better option, but if you need the Hatchery space, there's no choice.

As I said, in the meantime check out Farming in FAQ -- it'll speed up the process of getting enough gold to buy that Habitat.