Clip Art

Here are companies that buy clip art from cartoonists:

http://www.graphicsfactory.com/g-content.html

https://www.123rf.com/sellimages.php

http://www.canstockphoto.com/submit_images.php

http://depositphotos.com/seller-price.html

http://www.stockillustrations.com/Contact.aspx

https://submit.shutterstock.com/