The cost of an Apple TV monthly subscription is $4.99 per month.
That is after a 7 day free trial to Apple TV.
You can sign up for a free 7 day trial for Apple TV and cancel at anytime within those 7 days of the Trial if you're not happy with the subscription.
If you signup for the 7 day free trial to Apple TV and don't cancel the subscription within those 7 days then you'll be charged the $4.99 monthly fee to your credit card, debit card or Paypal account.
I pay the $4.99 per month for the Apple TV and it's well worth it.
Apple TV plus costs $5.00 per month or you can pay a yearly subscription for Apple TV which costs $50.00 per year.
I started paying for the year as it's easier than paying monthly.