My friend told me this little over 1 year ago when I started playing WoW. It's a good method for low level characters to make gold pretty fast.
You can do this with any level(you just got to avoid the mobs). Anyways you go to Raven Hill in Duskwood, it's like the first town when entering on the left. There will be an abandoned house in there, go inside and up the staircase into the room. There's a goblin in there I believe an Alchemy Vendor. Now he will carry one of these items at a time, about a 20 minute respawn if you don't see it just yet. He sells the Shadow Oil Recipe for 15 silver I think. This can be sold in the AH from 2g-5g. If you wait and buy about 3 and list them all your get about 10-15 gold on a new character. I used to do it, after a week I had like 70 gold.