Shaman PvP: Arena Gear/Honor rewards
Shaman PvE: LW. If you're too cheap, heroic badge gear/ZA. There are 2 elemental drops in kara (ring, BBW head) plus the lightning capacitor.
For the average 5-boxer, in PvE, Kara/ZA is unreachable. Which means LW/heroic badge gear is pretty much it. There's a few pieces of heroic drops you can collect, but collecting it times 4-5 shaman is rough. The good news is, if you take LW, that gear will last you to BT.