1. Think and Grow Rich by Napoleon Hill
First written in 1937, Think and Grow Rich has been re-published again and again over the decades. The author, Napoleon Hill was a multi-millionaire, and one of the richest men of his time. He claims that all self-made millionaires have certain things in common, and that even if they lost everything, they can get their money back again. He distilled success into 13 principles that you can take into action in your daily life. This book has inspired tons of future millionaires, and many of the modern-day self-help books out there with business advice are essentially copying what is said in this text. Believe it or not, it is just 55 cents on Kindle, and the nearly 11-hour-long audiobook is actually available on YouTube for free.