Well, I've also been doing a fair bit of thinking about this too. Long, but hopefully helpful post incoming:
http://www.maxdps.com/shaman/elemental.php is your friend. I've used this to plan out a crafted/PvP/Badge only setup which will be my goal after hitting 70.
I plan on the following, DPS stats in brackets based on maxdps data (default settings for stats), which is based mostly around putting spell dmg gems in sockets whenever possible. The aim being to max out their DPS from a PvE pov 1st, then build up more resilience gear for PvP later, then finally move onto arenas when I think I'm ready. The choices I have made are based on gear available through questing, crafting, PvP and Rep, and make little reliance on drops (exception being for belt, and a couple of common world drops, but you'll see why).
Shoulders:
1) Gladiators (40.99) - PvP
2) Pauldrons of the Furious elements (50.23) - 60 Badges
Neck:
1) Natasha's Ember Necklace (24.19) - Quest
2) Vindicator's Pendant of Conquest (31.37) - PvP
Chest:
1) Gladiators (49.17) - PvP
2) Netherstrike (55.62) - Crafted BoP
3) Hauberk of the Furious Elements (70.15) - 75 Badges
Wrist:
1) Auchenai Bracers (7.76) - Quest
2) Netherstrike (26.62) - Crafted BoP
3) Vindicator's Mail Bracers (32.92) - PvP
Belt:
1) Girdle of the Gale Storm (29.6Cool - Drop, and looks like healing item, but drops in BLOOD FURNACE, and is socketable, so will last a good while.
2) Vindicator's Mail Girdle (32.92) - PvP
3) Netherstrike (38.79) - Crafted BoP
3) Stormwrap (44.72) - 60 Badges
Legs:
1) Kurenai Kilt (53.45) - Rep - Kurenai Exhaulted (This maybe leather, but the DPS far exceeds anything else you'll get outside MH and BT - Although if you can get the Avalanche Leggings from ZA, they are an amazing 62.93).
Feet:
1) Greaves of Spellpower (21.00) - Quested , Turning Point (A/H)
2) Vindicator's Mail Sabatons (36.90) - PvP
3) Treads of Booming Thunder (46.61) - 60 Badges
Finger:
1) Ashyen's Gift (14.73) - Rep - CE Exhaulted
2) Sage's Band (18.59) - Rep, Honour Hold, Friendly (L60+)
3) Vindicator's Band of Dominance (23.13) - PvP
4) Seal of the Exorcist (17.93) - 50 Spirit Shards
5) Ring of Cryptic Dreams (24.23) - 25 Badges
6) Scryers Signet (26.12) - Rep - Scryers Exhaulted (I'm going Aldor, so not relevant for me, but really nice DPS)
Back:
1) Spell Slinger's Protector (16.81) - Quest
2) Torn Heart Cloak (18.89) - Quest
3) Cloak of Woven Energy (22.4Cool - Quest - Hitting the Motherlode (A/H)
4) Cloak of the Black Void (23.8Cool - Crafted - Quite Rare, but I've managed to pick up 2 on the AH already.
Weapon:
n.b. data on maxdps only has info for 2handers, and I'm going 1h and shield, so thinking of either:
1) Gladiator's Gavel - PvP
2) Gavel of Unearthed Secrets - Rep - Lower City Exhaulted
Shield:
1) Mazthoril Honour Shield (24.59) - 33 Badges
The only thing better outside 25mans is the Vengeful, and the Merciless requires arena, so not on this list.
Helm:
Lightning Crown - World Drop (Goes cheap on AH, and I've already picked up 4, dunno the DPS though, not listed on maxdps.com, but I'm not gonna waste mine. Other stats are crap, but it's nice Dmg for pve).
1) Stalker's Helmet of Second Sight (18.36) - Quest
2) Far Seer's Helm (20.62) - Rep, Kurenai Exhaulted.
3) Gladiator's Mail Helm (56.21) - PvP
4) Storm Master's Helmet - 50 Badges
5) Gadgetstorm Goggles (74.34) - Crafted - Engineering
NOTES:
- Data is based on alliance, haven't done any horde studies yet, but most will be the same.
- Also note that the Netherstrike set bonuses do not appear to be taken into account on the site, so including bonuses they may well push up the list (not done the theorycrafting on this yet).
- This list is based on DPS only, and might make you a bit squishy, I haven't started collecting any of it, but its a template to work towards. My main concern atm is that my Pally wont be able to keep aggro off the shammies if I get even half of it Very Happy
- DPS figures stated can be improved upon with JC BoP gems, PvP unique equipped gems or if you are lucky enough to have access to them, BT/MH Epic gems.
- In many cases, the Merciless and Vengeful gear is even better DPS than the bagde stuff, but you can look those up for yourself, that isn't my initial aim.
- The only non mail item I've considered so far is the Kurenai kilt, but you can also considerably up your DPS by going for cloth and somtimes leather items too, but this ofc ups your squishyness.
