Skinning is a REAL MONEY MAKER!!! I have a level 60 hunter who has both skinning and minning at pros.  My skinning is at 375 and I find that selling leather at AH is great.  You dont always have to sell full stacks of 20 to make the biggest return. As mention above, killing monster that yeild skinning is great for xp, and money, especially dragonkin, money drop, leather and xp!!