While the idea of getting something for nothing is undeniably appealing, it shouldn't hold true in the world of online graphics.
'Royalty-free' is a very different story. This important descriptive is attached to the service provided by the Vital Imagery Ltd. family of online graphic sites. These include Clipart.com , AnimationFactory , iCLIPART.com , iPHOTOS.com and Clipart.com School Edition
What 'royalty-free' means first is that when a person makes the decision to purchase a subscription or image they have access to millions of some of the world's best clipart, photos, fonts and animations without any hidden costs.
Another benefit of using sites such as those mentioned above is quality, ensuring a clean, crisp, professional addition to a project. Anyone who's ever used a 'free' image from a website knows it certainly offers no such guarantee.
Also, by purchasing artwork, the work of talented artists is being supported.
Perhaps the most important aspect of this however, is that using royalty-free images legally protects the buyer. Lifting 'free' images found on the internet is essentially theft and could land a person in a lot of trouble.
For more about this, here's a great article by graphic designer Chris Dunmire, which clearly outlines the risks:
Before You Steal That Image