(31 July 2014 - 12:22 AM)He may not be at the right level yet. You have to be at least level 20 to unlock it. It should show up right where yours is. This may have changed in the recent update, though. Give me a minute and I'll take a peak at it.
(31 July 2014 - 12:05 AM)By Sanctuary Offer, did you mean the Shop dragons being offered for x amount of gems for a limited time? There is often a delay in new dragon availability between mobile and PC. If you miss an offer on mobile, wait for it to be on PC, or vice versa. I've noticed that the better deals tend to be on PC. Sometimes it takes longer for a dragon to appear in the Shop on mobile than on PC.
(31 July 2014 - 12:01 AM)Once you've unlocked a level, you can breed a dragon using any combination that contains its elements. Even if you're on Sanctuary Level 5, you can still breed those at levels 1,2,3, and 4.
(31 July 2014 - 12:00 AM)Some of the same dragons will appear in future Black Markets, so you may stumble across it again. My advice, though, is to hold off on purchasing the boxes. Chances are that the dragon will eventually become breedable (if it isn't already).