On Thursday afternoon I put an eBook of mine (a home workout program) on Amazon. It took me all of 30 minutes to format the book, make a great cover, and upload it to Amazon. It was in review for 24 hours, I left early Friday morning for a fishing trip and I just got home. The book has already sold. At $4.99 a copy. It is by far the easiest money I have ever made.
So if you are thinking about it, just do it. Just make sure you are giving people something of value to keep refunds down and to keep those consumers coming back to you in the future.