Nintendo does not sell an official wireless controller for the NES Classic, although there are wireless controllers from third-parties you can purchase.
The NES Classic comes with a single wired controller, and it has a very short cable, but you have a few options if you decide to go wireless:
You can also purchase an extension cable for the controller if you’d like to sit a bit further away from the television.
It’s painful to use a wireless version of the NES controller when 8bitdo’s NES "Retro Receiver" brought Bluetooth compatibility to the original NES earlier this year. This is surely a cost-related decision and, if Nintendo wanted to hit $60, wireless controllers were surely out of the picture.