Although somewhat dated with its information on overall pricing, 3rd-party video products, and not listing what could be Today's used Mac (this was written 1999/2001), please check out Dennis R. Dimick's article:
Matching Old and New Macs with Video Cameras
(Desktops & TowersLaptops aren't covered)
This article has some very good cautions, pointers and recommendations for
Getting the best video bang for your Mac buck.