Phase 5 will add the questline for upgrading your dungeon set. This is actually really good for rogues, and I suspect many players will want to do it just for the completionism. The quest line requires materials and finished crafted goods and we should see a small bump in demand for the crafted goods.
Why do this?
To me this has seemed like a much less focused part of phase 5 preparation. Everyone is focusing on frost damage for viscidus, nature resistance gear and consumables and the stuff you need for AQ. The questline however has not been getting as much attention. I expect many hardcore rogues will have their materials lined up already, but there are probably tons of players who like me, has not stocked up yet.
The questline requires both raw materials and crafted items. Overall the raw materials will probably not see a huge spike, except in cases where the increase is significant relative to the current amounts on the AH. Some of the items will have higher demand in phase 5 in general however and should therefore see significant increases (Large Brilliant Shards have already started going up).
Most of the items you need are crafted items. Most of them are various intermediate crafting materials and you require items from a few different professions. Alchemy, engineering, mining, tailoring and leatherworking are all needed to assemble all the stuff you need.
The table below shows all the crafted items and the main materials needed to craft them. All of these items are candidates for crafting now and selling during phase 5. Some of the items are bound to daily cooldowns and have a capped supply like Mooncloth and Cured rugged hides.
In addition to the crafted items you need a couple of raw materials. There isn’t that many items here, but they are just as needed as everything else. The main one that stands out are Dark Runes from Scholomance. They are alongside the Dark Iron bars the only items that cannot be acquired solo.
Will the price change?
To get an idea of this we can compare the amounts one player needs for this quest to the current quantity available on the AH. The table below shows the percentage of the current AH snapshot you would have to buy to be able to finish your quest. The higher the percentage the more likely it is you will see a price increase. Enchanted leather and dark runes really stand out, but for the leather at least the base components are plentiful.
I think Dark runes, volatile rum and Dark Iron bars are the most likely to change significantly due to this, as they are very annoying to target farm solo. Anything with a 5% or up will also be in a place where a change can happen though. There are many rogues who will want this set for PvE, and if they all buy in the lull between phase 5 drops and the gates open we can see supply get wiped out quickly.
Items that will increase in demand from other sources
Finally we have to mention the items on this list that will see increased demand from other sources. Phase 5 adds new consumables, new craftables and a new raid. We can expect demand for a lot of these items to go up regardless of this questline and these items are prime investment candidates.
Large brilliant shard: Brilliant Wizard Oil, Brilliant Mana Oil, +15 NR enchant, new AQ glove enchants. These have already increased significantly and I expect that trend to continue
Arcanite bar: Titanic leggings, continued TF crafting
Black Lotus: Increased flask demand in AQ is likely
Firebloom: Brilliant Wizard Oil, Elixir of greater firepower, AQ war effort turn-ins, Dirges’Kicking Chimaerok Chops (as Rocket Fuel)
Cured Rugged Hide: Sandstalker NR gear
Enchanted leather: Obsidian Mail Tunic, Black Grasp of the destroyer, Dreamscale Breastplate (which seems like hunter PvP gear/NR gear for the chest piece)
The big unknown
How much does other players already have stocked up? That’s the big question we do not know. As such don’t ever invest gold you are not comfortable losing. Personally I would suggest spending some excess gold primarily on the most limited supply items on this list, which would include Arcanite, Black Lotus, Cured Rugged Hides and Volatile Rum for Rocket Fuel. LBS and Firebloom should also see sustained increases in demand and will likely never be as cheap as now again.