I've been obsessed with holographic things ever since the 90's stickers so it so exciting to see it coming into the fashions scene.
Two of my fave shops are stocking some designs:
O- Mighty http://o-mighty.com/products
Studded Petals http://studdedpetals.co.uk/
I'm going to go to my favorite fabric market when i'm back from uni to see if i can pick up some holographic material to make my own designs.