There is no 100% right answer for every server. Same places have higher and lower prices. But Uldum is very risky due to the number of botters and players there that report.
I farm obsidium in vashjir (no other people are there, so small risk of report), prospect it, make rings, DE them, sell enchants, and also i transmute carnelians into inferno rubies and cut them. Made 100kg in just over a week ;p
For me the best thing that works is doing alittle of all the cata areas. I farm no longer than an hour in each zone, never gotten banned in 8 months of botting and instead of having a huge stockpile of one herb and one ore i have some of all and they are easier to sell.
