The books are selling on Amazon for just under £5 for the paperback, and still at £1.53 for the ebook.
The links above are to Amazon.co.uk but they are available from all Amazons, also from Barnes and Noble.
I've also got a small stock of books at home, so if you'd like a signed copy send me an email via the Contact page above and I'll send you a copy (UK only, sorry).