New crafted gear from existing materials = big demand increase and a big cost increase. Elementium in particular will go very very high initially. I won't be surprised to see it sit at 100g / stack for a while. All the new crafted weapons are blacksmith recipes, and they'll all use elementium and hardened elementium bars. If you're clever you're stocking up on it. Also, very good chance epic gems are coming this patch, and also very likely they'll be prospectable from pyrite. So expect a HUGE price increase in pyrite. Good thing I've got 4 bank tabs full of it!!
Don't forget truegold, on my server it's dropped from 1500-2000 in 4.0, to around 500-600 since 4.1. Expect to see that go right back up too.
I'd be stocking up on volatile lifes too, they're around 8g each on my server, I'm predicting they'll be 18-20g each shortly into the patch.
Soooo much money to be made in the first few weeks of a patch! I love it!