I think it's also important to highlight commercial USB webcams, like the Logitech 922. They are kinda expensive but still cheaper than a DSLR and will get you all of the low hanging fruits over webcam quality. DSLR would get you benefit on top of that but arguably, given that 720p is the common webcam resolution, you wouldn't be missing out on much. Except maybe features like improved focus and depth of field effects.