Hi there! Not sure if this has been posted before, but I'll just go ahead and get it out there quick.
A few items recently peaked in price due to the release of patch 6.0.2 and the introduction of an item squish. I suppose most of you are familiar with the money you can make selling Imperial Amethysts, however, there's also a possibility to make quite some money by being and enchanter. The reason to that is that the "Weapon Enchant: Mongoose" is currently better than that actual MoP-tier weapon enchant for agility DPSers. Because of this, the mats needed for that enchant are selling like batshit crazy.
Just to take en example:
I sold 17 Void Crystals for 60 gold each in 5 minutes. I did also sell my two Large Prismatic Shards for about 40 gold each in that same time. Some other mats worth noticing are: Greater Planar Essence and Arcane Dust, which are currently selling for about 20 gold as well as 5 gold each.
What are you waiting for? Go farm TBC raids and heroics and make som goldz. Cheers, lads!