You have to kill ten elite vampires, not necessarily an easy task - made harder by the fact that elite vampires are fairly rare since the vampires stay pretty heavily farmed. When you turn them in, you get in exchange.... one restoration potion. Not really terribly useful in a pinch. I collected all these hearts, thinking I would get a potion of heal. :-P
And, then I promptly forgot about it for months, until someone mentioned it to me again today.
Considering the number of elites you've got to kill, restoration seems a paltry trade and not worth time or effort.