Well you will have to pay for postage, but it's usually around $2.10 - 2.25,USD.
Paperback and hard cover

All you have to do is choose a book you'd like to read from a list and you'll receive it in the mail.

At the same time, you list the books you want to get rid of. When someone requests to read it, all you have to do is pop it in the mail.

PaperbackSwap Club

Wish they delivered to Canada - grin!

I watch for the cereal boxes that offer something similar - actually get a brand new book of our choice for only $2.50 delivery - yipee!

A little 'off-topic' here, I know, but a local school raised over $4,000 from parents and friends donating pre-read books (soft cover) and then they held a fund-raising event, selling each for only $2.00.

And of course, there is always the internet, where you can read any book (not protected by copyright) for free. This includes all of the classical Greek and Roman authors (you can even find many of them in the original), and just about anything written up to (roughly)1910, including translations. Although I prefer the feel and touch of paper and binding, just as I prefer buying CDs to downloading music, the availability of all this important literature certainly can save poor students everywhere a lot of money they can spend at FAC.
Internet Public Library
Perseus Digital Library
Project Gutenburg
Z

Mhhm, its "virtually" free http://www.fullbooks.com/

WebScription has a bunch of free ebooks. Although I should warn you that they usually have the first and maybe the second book of a series free just to get you hooked. It is a nice store though because they come in many different formats, all unencumbered by DRM.