Alright, many people don't really understand how archaeology works, which has led to a great market to profit from; Keystones. That is, the Highborne Scrolls, Dwarf Runesticks, Troll Tablets, etc. Their droprate is somewhat rare, which allows be to sell them on the AH for anywhere between 80g-400g for the lower-tier races. What a lot of people don't realize is that they keystones are required for rare recipes; many people just use them on any common item they can, and once they reach a rare, are overcome by how close it is, and desperate to pay a lot of gold for one.
It really varies, all based on luck, but some days, I've been able to get 7 or 8 keystones in simply 4 hours of farming (with the odd battleground or dungeon mixed between) on my goblin warrior. This has been great for leveling, because between him and my bank alt, I have about 4500g, and I have yet to hit 85.