I've called in Asda on my way home from work and picked up a signed first edition of Siege by Simon Kernick for £8, I don't know if they have some at every store because i've never seen any other signed first editions on sale in any supermarket before.

I've not read any of his work before but for £8 if I don't like it I'll chuck it on the bookcase for 5-10 years and sell it later like I did with the Harry Potter books, If you do go for one the signed and unsigned were identical with the exception of a small black sticker denoting it as a signed first edition but both are the same price