Obviously you can go to the library or internet and read a book for free, but sometimes I like to own the books myself.
For starters, charity shops always have books. However, I am normally looking for a specific one and do not want to go to every charity shop in my city looking for it.
Here are a few books I've recently acquired:
Play.com have a huge range of books for great prices. I bought the anxiety one for £3.54, the self-esteem bible for £2.50 and Alan Carr's biography for £1.95. Free delivery.
They've been used before but I don't care, it's not going to affect how I read it.
Waterstones regularly offer books for people to read and review for their site. Follow them on Facebook or Twitter for updates on the books available to review. Then all you have to do is send them an email with the book you want to review and your address. There is only a limited number of copies for each one though so you must be quick!
The two books above are the recent ones I was sent and are new on the shelves. I've just sent off for 'Black Flowers' which sounds very good!