From browsing around i've established that the best webcam for me is the logitech c920.

However it seems that whatever I purchase, I'm either sacrificing the ability to digitally transmit live video to my computer over usb, or else sacrificing the ability to take pictures and video on the go. While some digital cameras can stream video with the use of some extra hardware they do not advertise this fact about themselves, and it works less efficiently than with a dedicated web-camera?

Is there a product that hybrid-ises the two features, having at least as good image quality as the c920 and also has its own internal memory store, and can be set on a tripod or a computer monitor, can stream video live over usb, and costs less than 120 (if only with price reductions)?

If not, then I'd be seeking a digital camera to accompany the c920, and it would need the following:
pause/record button that keeps the footage on the same video
image quality comparable to the c920 or better
preferably the ability to view video footage on the camera itself
cost less than 70.

Might be a tall order.