Figured I should put up a list of what is currently available for healing priests so they can get a NR set ready for AQ40. While you can coast through most of the encounters in your regular set, only drinking a Nature Protection potion every now and then, for Viscidus and Huhuran you will want a bunch of NR.
The number to aim for is 150 as a ranged caster.
HEAD: Dragonskin Cowl drops from Gyth in UBRS. Obviously you need the NR version to drop and while in other cases I've pointed out better versions to avoid futility of farming, there aren't any good choice unless you're an engineer and Rend farm groups are pretty common. That's +14 or +15 NR.
NECK: A quest reward from Silithus, which you should already have or be in the process of getting, gives +8 NR. It is also the only amulet with NR that is in the game currently so sucks to be you if you vendored it.
CLOAK: The T2 shoulders will lose their NR in 1.9 so don't bank on that number. You might have Cloak of the Shrouded Mist from Ragnaros for +6 NR or the Green Dragonskin Cloak from Emerald Dragons for +20 but the most reliable cloak you can farm for right now is the Grovekeeper's Drape from Mara. +10 NR and has some stamina. There is also a possibility of a NR version of a cloak dropping from Archivist Galford in Strat and Prince Torthedrin from Dire Maul but as both have only +15 NR and no stamina, I would recommend getting the Drape from Mara instead. And it's much faster to farm too.
CHEST: If you have your T2 chest, keep it. Come 1.9 patch, it will have +10 NR. If you don't have the T2 robe but you were lucky in Sunken Temple like me, you can blow the dust off your Embrace of the Wind Serpent and wear it for +12 NR. If you don't have either, then you better farm UBRS and hope that Solakar drops Polychromatic Visionwrap for +20 NR.
Obviously you would prefer to wear the T2 robe for its great stats and only wear the UBRS robe if nothing else works and you need those extra NR because it has no other stats.
BRACER: nothing good really.
GLOVES: The troll minibosses in Sunken Temple drop cloth gloves. These are great since they have either +19 or +20 NR. Drop rate is awful of course.
BELT: Chloromesh Girdle from Maraudon gives you +20 NR.
LEGS: There is only one option and no excuse not to get them: Cenarion Reservist's Pants. Completing the Armaments of War in Silithus will award them to you and +25 NR.
BOOTS: Farm Maraudon to get Vinerot Sandals. That's +12 NR.
WEAPON: Glowing Brightwood Staff can occasionally be found in the AH and gives +15 NR. The emerald dragons drop a NR staff too but if you can reliably get loot from them, you don't need a NR guide in the first place.
WAND: Shade of Eranikus drops a NR wand that gives +10 NR but a better choice might be Noxious Shooter from Mara as it gives +5 NR and has stamina too.
RINGS: The best rings have +20 NR and drop from Archaedas in Uldaman and the four drakes in Sunken Temple. But it's a 1/57 chance of one dropping. If you have completed the UBRS key quest, the Seal of Ascension gives +10 NR and if you're raiding at least MC, the Seal of the Archamagus gives +6 NR. I would recommend keeping the Seal of Archmagus as your first ring since it has good stats otherwise and then farming Uldaman for the +19 or +20 NR ring. Of course, you might be lucky and get Nightmare Engulfed Object from the Emerald Dragons...
TRINKET: Easy choice. Heart of Noxxion drops in Maraudon and you want two of them. Not only does that net you +20 NR but it will also allow you to cure yourself of 2 poison effects. Remember that the poison bolt volley that Viscidus casts also leaves a poison dot.
As for enchants, the Savage Guard enchants will not be in the game until 1.11 which is when all the really good craftable NR gear also comes in. So you should get the +5 all resistances enchant on your cloak and put the ZG priest enchant on your Gyth helm and Cenarion pants.
Remember that it is not any good to have 150+ NR as a priest if you have to devastate your stamina, intelligence, mp5 and +heal. You must find a good balance. Remember to get your Nature Protection Potions!
And for quick browsing while farming, the list of items you should get from Maraudon:
Heart of Noxxion x2
Noxious Shooter
Vinerot Sandals
Chloromesh Girdle
Grovekeeper's Drape
They form a decent base (+67 NR) to build upon and can be gained easily enough if you bring a friend or three to farm the Purple side.