I just rolled a new toon on a new server. All of my other toons are on a different server. On my 'main' server I have a chanter/banker alt, so I've learned the economy very thuroughly (at least for chanting mats and a few other related items). I have my prices for the various dusts, shards, and essences set and I'm happy with the results.
The new toon is also an enchanter (I never look a moneyhorse in the mouth). She's still farily new (lvl 18, 100 chanting), but already I'm seeing some whacked out economy issues.
On the new server, the lesser essences sell for nearly as much as their greater counterpart. Lesser magic essence sell for 25s while the Greaters sell for just 50s (3 Lessers make a Greater). So I'm making more money by splitting up my greaters. I'm just starting to get the astral essences, but it seems to be the same trend.
Now, as I'm typing this, I'm realizing that maybe this is the norm, and that my 'main' server is the one that's whacked out (the lesser essences sell for 15-10% of the greater).
Either way, when folks say 'it depends on your server,' it is most definately true!
P.S. couldn't resist yet another plug for dis-enchanting - lvl 18 warrior toon already has over 40g in her bags (and even more on auction) and has leveled herself up to 100. And she started from scratch.