Thinking about getting a document camera: Any suggestions?

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I'm thinking about getting a document camera for recording videos in the future that require writing on paper. I'd like it to have a USB interface that I can connect to my computer an screencast directly as if it were another webcam.

I honestly don't know what's out there, so if anyone is familiar with anything recommendable and not too expensive (I don't want to spend more than a hundred dollars or so), feel free to tell me your experience with any particular model.