posted 8 years ago
Are you asking about the new (rev 4) Apple TV which just starting shipping the other day, or the existing (rev 3) Apple TV. I have the latter, so I'll answer based upon that.
There is no monthly subscription to just use the Apple TV for mirroring or streaming video from other devices. Nor for playing audio or video from iTunes on a local computer.
For services such as Netflix, Hulu, Crunchy Roll and so on, you need to have a subscription to the service. This has nothing to do with Apple and you just pay for whatever services you want and use the corresponding app. I use the heck out of Netflix on the Apple TV.
You can also buy or rent movies from the iTunes Store.
So short answer is: no, there's no cost to using the Apple TV. Any additional costs are to buy content from other services.
I like mine a lot and have two on separate TVs.