|Public Domain Image Bowling Alley Red Ball White P:ins Lane form the Public Domain Archive|
Below are some links to some resources to check out in your search
Trying to save money, there are 3 paths to look at, Public Domain, Royalty Free and Creative Commons 0. This article from Inc magazine breaks there areas down and gives you 20 great places to look.
20 Sites With Free Images for Your Blog or Social Media Posts. Some of the leading site that people use are Pixabay, 1 Million Free Pictures and Flickr: Creative Commons, and one they don't mention is the Library of Congress. Be aware of all your rights and that your image is free and clear.
13 Sources for Free Public Domain and CC0-Licensed Images from wptavern.com also has some great sites, some of them overlap.
You can always go with stock images and there are tons of sites to look at. Advantages are that you know your license will be fine. A number of the stock houses like ShutterStock.com have changed their license a lot and now allow for using their images in ebooks and print on demand. They have also gotten much more competitive with pricing, so images are much more affordable. Check out the list in our Resource area
Image above from the Public Domain Archive with 100% Free Stock Photos, Every. Single Week