I got into beta around a month ago and you do not use any of the old enchanting materials for anything (worthwhile anyway) past 375. Right off the bat you start getting "Infinite Dust" and "Cosmic essences" from green drops up in Northrend.

I started dumping all the things I've saved up in my bank two days ago and I've made about 2100g so far. My advice is to sell *before* Blizzard sets a release date. I don't know about other servers but back when BC was approaching, as soon as a date was set the whole market on my original realm went belly up. I ended up having to just flat out vendor or delete things.

**Edit: I might add, I leveled enchanting on my main Druid from 0-375 in NO time at all just from arcane dust and planars, and a few herbs here and there for oils. Anyone who actually weights the material cost on skillups will not buy voids or LPS's to get to 375, so sell what you've got IMO!