Here is a list of the sites where you can buy images from. Paying for images usually means higher quality, more choice and licenses that are clear.
http://www.canstockphoto.com/
Are a royalty free stock photography agency that believes professional stock images should be affordable and accessible to everyoneThere are over 25,000 top quality images each day from the world's best photographers and artists.
http://depositphotos.com/
Royalty-Free Stock Photos, Vector Images and Videos
Millions of high-quality royalty-free stock images and high-definition footage at the best prices to fill all your creative needs.
https://en.fotolia.com
Fotolia is a world-leading image bank, providing instant access to over 44 million images, vectors, illustrations and video clips, to ensure you'll always find the one you need.
http://www.gettyimages.co.uk/
Getty Images creates and distributes world's best and broadest imagery collections, making them available in the most accessible and usable way -- 24 hours a day, everyday. Including news, sports, entertainment and archival imagery.
http://www.istockphoto.com/
iStock by Getty Images is the web’s original resource for crowd sourced royalty-free stock images, media and design elements, offering millions of hand-picked photos, illustrations, videos and audio tracks.
http://www.shutterstock.com/
Over 60 Million Stock Photos, Vectors, Videos, and Music Tracks. Find everything you need for your creative projects.