Ok guys, I just thought of this a bit ago, and thought you might like it, I don't believe this is was posted before, but I searched anyway, couldn't find anything. Anyway, here goes:
In Shattrath City, there is a portal to The Isle of Quel'Danas, in front of it is a Draenei, and, if you are 70, has a daily quest for you. This is called Maintaining The Sunwell Portal ( Maintaining the Sunwell Portal - Quest - World of Warcraft ). It requires you to go to north Blade's Edge Mountains to Bash'ir Landing and get Smuggled Mana Cells.
Now, if you do Blade's Edge Dailys, this is a great side daily, takes only a few minutes. Just kill ethereals until you the the Phasing Device, then use it, you can now see the cells, and the PHASED WYRMS that guard them. This effect lasts until you log out, die, or leave Bash'ir landing.
Now what I'm saying to do is to farm the wyrms. You won't get competition from other players, they just want the cells, and many people don't even do the quest, the drop motes of mana rather frequently, and are very easy. Just farm for a while, and you'll have several primals in no time =). Primal Manas usually sell for around 20-30g depending on serever, I made about 200g from 2 hours of farming.
Enjoy