Linear Algebra is a text for a first undergraduate course. It is Free. Use it as a main text, as a supplement, or for independent study.
Get a printed book
You can get a paper copy by clicking on this link to Amazon (that is an Amazon affiliate link; note that I get a fee if you buy). A new copy is close to the cost of media, about $28.
Please note: some people other than me also sell the text, with no money for me. These other people list a lower charge on the page, but note that if you buy it from Amazon for less than $25 then they will bill you for shipping and it will end up costing you more than the $28 that I list.
If you are thinking teaching out of this text then note that you can register with OpenIntro.org to receive a free paper desk copy (this organization works to make texts like this one easier to adopt).
Are you teaching with this?
You may find useful a number of ancillary materials, including beamer projector slides and a lab manual using Sage.