Easiest would be, in a way I would do it:
- Farm Uldum or any Cataslysm zone which can spawn Pyrium to make the Truegold bars. (you will need an Alchemist to make the Truegold, it has no more cooldown).
- You will need a herbalist to farm the herbs to make the Cataclysm potions (Alchemist needed, again).
- You could fish-bot the Fish needed to make the Oil (last material) but in my opinion it's cheap to get and easier to get on the Auction house.
Needed profiles: Herb/Mining in Cataclysm zones (the forums here have a wide variety of profiles for this)
Manually make the Vial (if you already have the recipe) and ding ding cash.
If you need more information on which profiles I use to farm Cataclysm mats I can give them to you, or write a more in-depth guide if requested. It should be pretty easy to get the materials for a Vial in 8-12h tops, depending on the mining/herb competition on your set Cross-Realm Group.
Good luck !