As I was levelling my lvl 38 twink/alt through stranglethorn vale, I would mail some items off for my bank alt to sell, and some to sell in the Auction House so as to make some gold on the side.
After a few days of about 15 minutes each, I realise that there is a very good opportunity in this untapped market. Here are 2 things to watch out for when you are in the area!
There's a tiny little island towards the northwest of Stranglethorn Vale which is full of water elementals, they have the best drop of elemental water that I have ever seen so far. Elemental Water is used for many recipes and goes surprising well on the medivh Auction House, from 15-25 gold. Do take care to post only when there are no other competing Elemental Waters on the auction house however, so as to maximise your profit. Trade volumes for this item are low however, so there should be plenty of opportunities to make some gold of this!
2) The green hills of stranglethorn:
Everyone knows this papers drop all over the place in this area, but it doesn't occur to many that there is a Neutral Auction House right in Booty Bay where they can immediately trade and sell these quest items! Alliance and Horde on medivh will both be looking for this items to turn in for quick experience, and you could be the one to sell them each piece for 1 gold to 5 gold.
Once again, make sure there are no competitors before you post your goods!
Update: Shacknews did an interesting article over what kaplan(tigole) said about the Green Hills quest, I intend to post about it soon.
Here's to your low level hero making some gold at 40!