iStockphoto

iStockphoto is a collection of royalty-free photographs, vector Illustrations, Flash files, and Video clips. If you start a free account yourself, credits are around $2 each, with a minimum purchase of 6 credits for $11 (as at 29/08/12). Images generally cost between 1 and 150 credits, depending on the size and image collection. Depending on the original size of an image, it can be bought in XSmall, Small, Medium, Large, XLarge, XXLarge and XXXLarge sizes. Visit their website here: www.istockphoto.com

fotolia

Fotolia offers an image bank of millions of affordable royalty free images, vectors, illustrations and video footage clips. Some photographs are offered for free while those that are sold can be priced from $1 to as high as $2,000. Credits need to be purchased online to buy images. Visit their website here: www.fotolia.com

Microsoft office clipart & imagery

Microsoft Office offers an image bank of free photos and clipart. Visit their website here: www.office.microsoft.com

dreamstime

Sign-up to Dreamstime for free and access low prices for Royalty Free stock photography. They offer a collection of 14,000,000 images & illustrations. You will need to purchase a plan to download stock photos - high-resolution stock images are as low as A$0.22/image or free (as at 29/08/12). Visit their website here: www.dreamstime.com

shutterstock

Shutterstock maintains a library of royalty-free stock photos, vectors, and illustrations available by different time length subscriptions. Visitors can browse the library for free, and can then license and download images through a variety of available packages. Visit their website here: www.shutterstock.com