Digital clip art collections provide a great source for designers to obtain inexpensive (sometimes even royalty-free) images. If you're considering purchasing a digital clip art collection, here are some questions to ask:
As you search for images, don't forget to check the Library of Congress web site. In addition to copyrighted images, their online catalog of prints and photographs even includes a number of quality images in the public domain, as well.
Old magazines and books are another potential source for images. Any that were published before 1923 are in the public domain. Those published between 1923 and 1963 might be in the public domain, unless the copyright holder renewed their claim. Anything published after 1963 is still under copyright, so you'll need to obtain permission before using it.
And finally, our print shop has a number of print-quality clip art collections on file, too, which you are free to browse.