I sold the virtuoso inscription ink kit once for 20g. Perhaps the dude that bought it makes more gold than the time it takes to track down the inscription vendor. I was thankful to say the least. People love buying patters too that you can purchase at a vendor for 50s or so.

I used to make some money selling Manuals of Heavy Silk Bandage.

Only one vendor for the Alliance sold it. He was hidden in Stromgarde Keep. Most people didn't even know he existed. You entered, turned right, turned right again, and turned right again, there he was.

As the pattern was not taught at a trainer, it was a required item to level First Aid. I would buy them for 55s, and sell them for 4-5g. This was back before gold was extremely easy to make, and if I remember correctly, Quel'Danas hadn't even been implemented yet, so the idea of hitting a daily area and making money didn't exist. Some people eventually noticed, and started copying me. Ending up in a selling war. The idiots eventually started selling them for 55s, the same price to buy them. After a couple times of this, I just stopped. It's pointless to sell an item for the same price you buy them, THEN have to pay AH fees and cuts.