Added another little paragraph about leveling through the garrison exclusively, though it would be more a long haul type situation.Wowhead has a guide on how to do exactly this. You do bonus quests in Shadowmood, Gorgrond, and Spires except for one kill, then chug the elixir and the one from your garrison quartermaster before flying a route to pick up treasures in the zone. Then you finish off the bonus quests.
The Savage Gift from the Winter Veil garrison dailies has a chance to drop the elixir, a mount, or a 50 ilvl follower boost.
Yes I am collecting the Savage Gift everyday (I don't really care for the decorations), I already got the mount and am hoping to save 3k gold by getting some more elixirs for my other alts, as I have not gotten the rare mission in the last week.