If you have been watching the excellent American TV adaptation (best thing on TV at the moment imho) cheapest I can find this collection of the first 8 books the series is based on
The first eight volumes of this fan-favourite series collected into one massive paperback collection. Get it while supplies last. Collects The Walking Dead, issues #1 to 48, written by Robert Kirkman, with art by Charlie Adlard and Tony Moore, cover by Adlard and Cliff Rathburn.
Image, paperback, 1,088 pages, published September 2010 (new edition)