I am not sure if there is enough time left to get a return on investment in terms of gold if you don't have at least one optimised garrison (with or without an optimised shipyard).
If gold making is not relevant in this regard (you could farm Cata heroic raids instead, for example), I would only bother with some of the buildings - tavern for getting dungeon quests (some reward toys, or items that will become toys), menagerie if you are into pet battles (also barn level 3, because you can get a pygmy cow from there), fishing hut if you are into this, stables if you are into collecting mounts.
I would get a level 3 garrison for the shipyard to get access to Tanaan, though - even if you don't bother with it afterwards. There are some more items to collect (pets, mounts, toys), and you can farm gear which would surely help you when you go into Legion.