For balance leather, look yourself up on armory and use the "find an upgrade" function.  Ignore the uber-raid, cloth, and healy items at first as you scan down the list.  It will tell you where to get each item.  It takes time to get them, but they are out there.  There are some pvp items, yes, but you can also get what you need from 5-mans and karazan.  You may have to gear up in stages to qualify to get the better ones.  Some of the healing leather can even fill in for a while if gemmed right.  Also, you can wear four t-4 and the complete (crafted) Windhawk set for multiple set bonuses.