I'm wondering if there is a 'definitive' answer to this.
When I was Alliance on Proudmoore I could prospect about 1.5k worth of ore, cut rares, sell uncommon. Go to sleep, wake up with full inbox, about 4k profit.
Illidan is just downright fucking horrible for this.
I make the rings/necklaces, sell the blues, mail the greens to my enchanter, DE, make into scrolls, cut rares on main.
I lose out not a little bit, but a ton of gold by buying the ore and prospecting it.
Scrolls don't sell, blue necklaces/rings don't sell. Even cut gems barely sell. I only sell the delicate cuts. Everything else always comes back to my inbox.
I know there a lot of servers that are good for doing this. If you do this quite successfully even just name your server. Severely contemplating a server change cause this is ridiculous.