I'm starting a new thing at Diablo 3 Gold Guide, where I talk on this blog about markets that many players have long since forgotten.
How much do you think this level 30 helmet cost? How much do you think I flipped it for?
To answer these questions, you first need to understand the stats a player is looking for when they buy a helm at level 30. Primary stat, Vitality, and Socket. The gold find, the small amount of strength, and the poison resistance are not helping the value at all. But the intellect, vitality, and socket make this item worth a lot more than you'd think.
Now, for the price. I bought it for 5,000 gold and sold it for 250,000 gold.
I'm pretty sure you could do this, even if you're broke. To make things even sweeter, there were literally no helms on the auction house that had primary stat, vitality, a socket, and level 30 besides this one.
It's important to understand that cain's helm is pretty good, despite being many levels lower, so you have to compete with those kinds of legendaries when you sell these rares. A high primary stat with vitality helps achieve this. Having something like +crit chance or chance to fear will also push a helmet into the million gold or higher range even at level 30.