Important edit: I recommend buying books if you can afford it. Many reasons for this. One, it's fun to receive packages in the mail. I get a rush every time I rip a package open. Two, it's good for the ego. It helps you keep perspective on how much you've been reading. Three, you can underline the books as you read them, this can be VERY helpful. Unfortunately I do not recommend loaning books to friends, you will never get them back.
Awesome! You can start by reading 1 book a week, which is an aggressive but doable goal. To some it may not sound like much but if you have not been making a habit of reading regularly, it will take you a while to get back into it. In a year you will have read 52 books. I am of the belief that compound interest is most effective when you have staggering sums of money. It is second most effective when it comes to knowledge.
Amazon will sell you books for cheap, but there are many business classics that will probably be available at the local library. I bet your local library will at least have one of these seven books:
How to Win Friends and Influence People by Dale Carnegie
Think and Grow Rich by Napoleon Hill
Seven Habits of Highly Effective People by Stephen Covey
{anything} by Seth Godin
Positioning by Al Ries
Getting Things Done by David Allen
21 Laws of Leadership by John Maxwell