For people who like to read alot, I have started using this website: http://www.readitswapit.co.uk
You basically upload a library of books that you're willing to swap and then you can swap books with people from the UK. You just have to pay to send your book (usually about £2.60 in my experience). So that's not necessarily cheaper than second hand, but the big plus is that you can pick out specific books you want - I've found somebody with every fiction book I've wanted so far (and there's lots of non fiction too), even new books
There's a rating system where you rate the person you swapped with after every swap, so people quickly build up good (or bad) feedback so that you know the person you're swapping with is reliable and actually going to send the book.
You basically upload a library of books that you're willing to swap and then you can swap books with people from the UK. You just have to pay to send your book (usually about £2.60 in my experience). So that's not necessarily cheaper than second hand, but the big plus is that you can pick out specific books you want - I've found somebody with every fiction book I've wanted so far (and there's lots of non fiction too), even new books
There's a rating system where you rate the person you swapped with after every swap, so people quickly build up good (or bad) feedback so that you know the person you're swapping with is reliable and actually going to send the book.