To order it on Amazon [U.S.], follow this link — it’s currently priced at $17.16 (34% off). For Amazon.co.uk [U.K.], this link — where it’s £12.34 (35% off). You’ll thank me later when you find that you got a first printing (as I hope you will; its sales rank is already pretty high). The release date for both the American and British editions is May 5, 2009.
NB: Thanks to Ardamir for the updated link to the British edition. I had unwittingly linked to the more expensive Special Edition — which also proves that I have basically no sense of the value of the British pound sterling. :)