The Amazon Fire TV Stick is on sale for $30. Plugs into a TV's HDMI port, and streams Amazon Instant Video, Amazon Music, Hulu, HBO Now, Sling TV, and others.
Note that Amazon and Google do not play nice with each other. If you want to run streaming video owned by Google, such as YouTube and YouTube TV, consider a $35 Google Chromecast or a $40 Roku. A Chromecast works directly from more apps with a "Cast" button that appears. A Roku has the most flexibility, supporting both Amazon and Google apps.
We chose Chromecast over Amazon and Roku for its performance. Videos load faster than Roku, and quality seems better. It also works great with the YouTube TV app, which we chose over Playstation Vue, DirecTV Now, Hulu TV, and Sling TV.
However the Amazon Fire Stick does have voice-operation built-in, a nice feature. To get voice-control that with a Google Chromecast, we had to buy a Google Home.
One more thing to note, Net Neutrality rules expire today in the US, allowing service providers like AT&T, Verizon, and Comcast to block and slow access to services that compete with their interests, like video streaming services. Changes will be slow for them to implement, but how people access digital content will eventually be determined by contracts with the cable companies, versus the Net Neutrality way of consumers paying for sufficient bandwidth/speed to access the Internet. The new normal means websites and streaming services could be slowed or blocked from homes, explicitly allowing cable monopolies to prioritize content that pays them. This sounds confusing, but think of it like your post office slowing or refusing to deliver mail from certain businesses even though they paid the same postage as another. Unlike FedEx, UPS, or any courier service who can compete with the post office, there is no alternative Internet access for most homes in the US. Since there's no competition for the majority of Americans, people who see their video streaming services degrade will have less freedom of choice. We fear that less competition will lead to higher prices and worse service for consumers accessing video streaming services.