I'm kindof the opposite opinion to many here.

Liquidate EVERYTHING.

Get your skills up to 375, then pack up to powerlevel inscription. Then sell, sell, sell. About a month ago, I had a stack of primal mights 2-3 stacks of every primal, 4-5 stacks of every outland herb, 5-6 stacks of voids and prismatics, over a dozen stacks of dust and half a dozen essences, stacks of every ore, bar and gem imaginable, and I got rid of most of them. Once the xpac hits, everyone will want some of this stuff to skillup, sure, so you'll make a bit right away, but then it's useless, and you'll be stuck with selling items for half price or less. Making matters worse, DK's will be leveling mostly in outland. Provided they can skillup enough to gather in outland, you'll see an market shift of old world items as they powerlevel gathering and crafting professions, then more outland items as they level through to 68 that no one really will want. The smart people will have all the mats saved to powerlevel DK crafted professions, going from 1-375 in a day (I have inscription and JC mats sitting on an alt atm) so they won't be buying anything, just selling.