Can somebody recommend a cheap USB webcam that works on 2011 iMac running lion?

I'm a drummer who sometimes posts videos on YouTube. Sometimes I want an overhead shot of the drums and it isn't practical or safe to hang my iMac 21.5" over my head to shoot the video with the built in camera haha! I tried an old microsoft lifecam and a Xbox live cam but neither worked. I want to use moviemaker. Thanks!