Since 5.0 Strath has now been revamped with completely new bosses and mobs, why does this matter you ask? with the revamp 2 patterns can no longer be obtained. These patterns are:
Pattern: Robe of the Void (Pattern: Robe of the Void - Item - World of Warcraft)
&
Formula: Enchant Weapon - Lifestealing (Formula: Enchant Weapon - Lifestealing - Item - World of Warcraft)
Both of these were quite common so they did not cost much on the AH, at the moment it is not very widely known that they are unobtainable now so use this to your advantage! In the past few days I have managed to pick up 5x enchants (all under 50g/ea) and 2x patterns (both under 200g each) Buy as many as you can for a reasonable price and just wait, the price will only go up now - the longer you wait the more gold you will make.
Dirge's Kickin' chimaerok chops are a great example, this cooking recipe was removed during the shattering and now sells anywhere from 50k upwards of 300k. Collectors are willing to pay big bucks for these items once they become rare. Good luck!
Note: Bizzard have put previously removed items back into the game in later patches (e.g. executioner enchant) So please don't spend gold if you do not want to risk it.