Here's how I found this site. Each of these sites have really great shapes to offer. Deviant Art and LadyOak are awesome.
About the images, Tamlin is right. You get what you pay for. If you need something from those sites why not pay as you go and not get stuck into expensive monthly memberships? That's what I do. When you have to have the quality for projects like print (posters) where larger size files are a must, free photos just don't cut it when it comes to quality. If you are being paid for a project simply add add the cost into the charge of the design. You might have to foot the bill first but you'll be re-paid.