Amazon's Kindle has some amazing offerings of zombie literature - and lot of it can be gotten for less than a buck. Many others can be bought for $1.99 or $2.99 (and, of course, Night of the Necromancer for $3.99!)
I've recently read two, and am working on a third. I read Amanda Hocking's Hollowland, a very entertaining zombie tale that's very action-packed that has interesting characters - though the ending leaves you hanging a bit and opens the opportunity for a sequel. It's definitely worth the price, and I like the use of a tough, female lead. While the romance is obviously meant to appeal to teenage girls, I still thought it was quite entertaining.
I also recently finished After Life by Jaron Lee Knuth. The story chronicles the lives of two childhood friends, Alex and Morgan, surviving in an apartment in Minneapolis during a zombie apocalypse. It's decently written, and also very much worth $.99. It also has a very unique take on zombie mythology with an idea I hadn't really thought of before - but since this is somewhat of a twist in the book, I won't reveal it here.
Currently, I'm reading The Becoming: Outbreak, by Jessica Meigs. I'm one chapter in, and so far, so good. There are three books in the series, but currently only the first two are out. I'm excited to finish this one and follow the story of survival in a zombie-infested Atlanta.
So anyway, check these books out. A buck ain't much, even in this economy. By the way, I tried to post covers, but they didn't look good on the blog. So, just follow the links to see them.