I read about this on the official WoW forums, and tried it out..works pretty well.
Buy any stack of Netherweave Cloth at the AH for LESS THAN 3 gold. If you spend 3g per stack, you will break even and won't make any profit.
Then create as many Heavy Netherweave bandages as you can.
Then sell them to vendors for 6g!!
Example:
Buyout 2 stacks of netherweave cloth at 2.5g
Creates 1 stack of H.N.B. which sells for 6g
2 x 2.5g = 5g
6g - 5g = 1g profit.....from doing practically nothing!!
it may not be the quickest way to make a profit, but hey...it works!