To get streaming services, you need a smart TV (for internet wifi access). Our 12 year old TV (as with most old ones) is a dumb TV, but does have a USB port.
Roku plugs into the USB port, thereby giving internet wifi access. The (as of yet uninstalled) roku I bought on sale at Target for $28 has a regular price of $40.
Roku's FAQ page lists several services which provide the actual content -- fubo, hulu, Philo, Sling, and YouTube TV. From looking at their websites (some helpful, some pathetic unless you agree to sign up), Sling seems to be the best deal. Two options -- blue and orange, both $30/month with slightly different packages of channels. You can add other packages of channels for an additional $5/month.
So, it looks like for a $60 upfront cost for antennal and roku stick, then $35/month, I can get what I want to watch vs paying $100+ a month for DirecTV. No wonder cable and satellite companies are losing customers in droves.