I would like to suggest keeping a small stash of Arcanite bars in the vault if possible.
They are difficult to get hold of quickly, warlocks need 1 for their fast mount and enchanters need 3 for to level enchanting around the 290 mark and I would imagine other quests and profession skillups require them too.
I have been very lucky tonight in being able to get most of the guild alchemists to step in and help me out. I still have quite a bit of thorium left over and a couple of crystals and should hopefully have a few bars spare which I will put in the vault for now if that's ok?
I suggest in future if everyone agrees that every now and then our guild enchanters convert donated crystals and thorium if they can spare their cool downs to help other people level?
Wow, that came out as a much longer, rambling request than I thought it would!