Clay is available in the UK, America and Australia from all the usual channels, with an RRP of £14.99 (hb), and £7.99 (pb). There is also a Kindle version.
Please consider purchasing Clay from your local bookshop; you can find yours by entering your postcode here. In the UK it is also available at a discount direct from Bloomsbury, Guardian Bookshop and Caught By The River, and Big Green Bookshop can send you a copy with free postage.
Alternatively, you may order a copy from Amazon here.