As a freelance photographer what you need to find is an image library that has 'Royalty Free' images. Any other would be for single use only. For high quality pictures the price is not going to be cheap. You have to remember the time effort and expertise that goes into getting those sort of images in the first place. They are usually taken on profesional equipment and quite rightly the photographer would have wanted a good price for the image library to buy the picture copyright outright.