Farm Netherweb Spider Silk, this drops from different spider mobs around outland, one of the best to farm is Dreadfang Widow in Terokkar:
Dreadfang Widow - NPCs - World of Warcraft
By farming this you will usually get about 40 spider silk per hour (usually 4g each at AH), usually more+tons of grey vendor loot (1g stack) aswell as green items.
These are great to farm if your gear aren't that good, or when you are in BG queue o waiting for instance.