Regaurdless of how good the webcam is, you'll still get grainy issues and poor quality.
Webcams aren't designed for high resolution photography, think of it it like a camera phone. Theres pretty much no phone around that will give you the image quality of a digital camera lense.
In the past I've had a Logitech Sphere, Bought it for £99.99 ($150) and even with high end cams you wont get very far.
I know there are some 2 MP webcams out there maybe 3MP now, you could look at getting one of them, just don't expect perfect picture clarity
