With over 63 million photos, vectors, illustrations and video clips, Fotolia is an option you won’t want to miss out. They offer a variety of ways to pay, such as subscriptions, pay-as-you-go, and monthly packs. Their community of photographers, artists and agencies bring tens of thousands of new graphics to the site every day. They have some nice looking stock photos; you should take a peak.
Fotolia is a smart place to start when looking for stock images or videos.
Free images can be linked to here.