There's the possibility that more than one of each breed will be available, but right now that isn't the case. Even if it were the case, the nightmare dragon would still be unavailable. That breed is exclusive to Merrik Tetra's bloodline. In other words, only Soulserenity gets to have a Nightmare dragon.

These are the ones that are [i]probably[/i] available:
Blue
Gold
Yellow
Pink
Red

Note that since I'm not the GM, I don't have the actual list, I literally just copied one posted a few pages back. One or more of these [i]might[/i] already be taken.