I posted this a few weeks back at £14.93, but now it's even cheaper.
This is anime like you've never seen it before.
In a long-forgotten walled town, humans coexist with the Haibane, angelic-like beings of unknown origin. Rakka becomes the newest Haibane after she awakens from a strange dream and finds herself hatching from a massive cocoon. With no memories of her previous life, Rakka struggles to adjust to her new surroundings, however, burning questions remain in the back of her mind. What are Haibane and what is their purpose? What lies beyond the huge, forbidden town walls? Thus Rakka begins her wistful journey of self-discovery and wonderment.
Contains all 4 volumes.
Edit: I've seen it now a little cheaper at thehut.com @ £12.85