some people say 5g some others say 20g and i dont kno who to believe
You don't need 100's of g at level 12. Just start running instances or what not don't bum gold, I hate when nubs bum gold. Another option is to play the auction house. Find mats really cheap and buy in bulk turn around and sell it for a gold or two less than AH price. I have made a LOT of gold doing that.
look at what there at now 5g per stack of 20 sounds right or just get auctioneer addon