Well from beta testing and playing the full version I have yet to find the vampire hood that is apparently in the game. I'v found many random encounters of vampires ect... but none have/wear them besides Serana. Is there anywhere to find one easily or do you have to find one in a random encounter?

Seranas is unobtainable. But, the "vampire hood" can be obtained through DG radiant quests to kill the vamp pretending to be an advisor.

It's a recolored cowl. Color matches hers, but looks quite different shape wise.