However, many authors do not have the talent or funds to create a unique cover (or have one created). CreateSpace conveniently offers a cover creator template that allows you to make your own cover. No matter how strapped you are, I don't recommend using the stock photos. Why? Because they are easy to pick out, especially if you have used cover creator. I do use a stock photo for my study guides, but most people buying study guides are not exactly looking for a fancy cover.
It is easy to find royalty-free stock photos that have expires or no known copyrights to upload for your cover design. Check out Flickr , CanStock, Wikimedia Commons, and even places like NASA. You are looking for pictures whose copyrights have expired or whose creators are licensing under the GNU free use (U.S. government photos are copyrighted by the citizens of the US and open to their use). (You should always cite the creators of your cover images. I recommend doing it on the copyright page with "Cover image by") You will not be able to copyright these images yourself, but they are frequently more impressive than the standard CS or KDP stock photos. Here is a cover I created from some old images of paintings:
Finally, you can find freelancers who are willing to design your covers at reasonable rates on freelance websites (Guru, eLance, etc.). Expect to pay $50 - $300 for good cover design. Here is our latest release: