Heaphones
I use the Philips SHB9100 Bluetooth headphones. They come with a cord to use the headphone jack when Bluetooth is unavailable or if you run out of power.
The 3.5mm cord is a little short for me but similar cords are readily available.
Cost varies but I paid $99 at T-Mobile about 2 years ago.
BTW I have only seen the batteries die once.