I just installed a wired one, pretty easy, as I already had ignition switched power to the top/front roll bar for my tablet, phone charger and refrigerator freezer (okay, I lied about that last part).
$50 for camera and display. I did have to make a wedge to mount the camera, as the roof is sloped, and the camera wouldn't declinate down enough to see the jack I have mounted for a back bumper. I wanted to see up close to avoid puttin a wheel over a mountain trail switchback where you have to go forward/reverse multiple times to make the tight corner. Ended up being a clean install, comes on with key, but if not needed there's an easy to reach button on the display to turn it off.