But the most interesting and telling reason for why TVs are now so cheap is because TV manufacturers have found a new revenue stream: advertising. If you buy a new TV today, you’re most likely buying a “smart” TV with software from either the manufacturer itself or a third-party company like Roku. The cut of the advertising revenue from those pre-installed video channels is big business for actual TV makers, as is the business of selling user viewing data and other information to marketers.