First of all, I'll be honest. I won't do as much as I could.
A new tier of gear means a new raft of gems to be sold, and gear to be enchanted. What ever is 'hot' now, will become hotter. So, the usual suspects - Inferno rubies; cut and uncut, celestial essence, and heavanly shards will be popular. For me - this means I need to put away more inferno rubies and their transmute mats : carnelians and heartblossom.
There is also a bit of talking about transmogrification. Now, I do not pretend to know what will sell and what won't. I will leave that up to Kaliope and the like. However, some of it is likely to be old world crafted gear, needing 2 things : recipees and mats. Personally, I probably won't purchase much old world, but what I do have for crafting vanilla, BC I will now sit on until 4.3. I have some very rare patterns. Come transmogrification, some players will have to catch them all. I want to sell these to rich bored players.
Market UI without typing against mistakes - In every game the market UI is a long table full of numbers. You must scroll and find the one you want to accept. You can easily get lost between hundreds ...
16 hours ago