I've tried farming a few different places at my current lvl  (lvl 44). 
So far it seems like the Vilebranch Troll mobs in the  Hinterlands are by far the best farm mob I've found. They range from lvl 42 to  lvl 50 and there are several elite types. 
http://www.thottbot.com/?s=vilebranch 
The biggest  money maker they drop is 'Wildvine'. 
http://www.thottbot.com/?i=4373 
-It's used for  Wildvine Potions 'Restores 1 to 1000 health and 1 to 1000 mana 
-Used by  engineers 
-Used by tailor 
-Used by leatherworks 
-Required to  complete the Leatherworking Wild Leather work quest (two of them). 
The  AH fee is only like 30c - so there's very little risk and a stack of 20  wildvines can sell for 5g easily. 
From the trolls you also get  
-Troll Necklaces: A repeatable quest that gives you 390xp @ lvl 44 for ever  5 of them you turn in (ALLIANCE) 
-Mageweave 
-Silk 
-Silver 
-Flask  of Mojo (used for 4 different recipes and an item for a couple of quests: http://www.thottbot.com/?i=3159) 
So you've got  several money making drops with the Wildvine possibly netting you 5g an hour  alone. And if you are part of the Alliance - the NPC right at the Aerie Park  entrace give you around 390 xp for every 5 troll necklaces you turn in.
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