On Wednesday Apple introduced the Apple Watch Ultra, a $799 wearable meant for people partaking in extreme activities like climbing mountains, running ultra-marathons, or diving. But as MacRumors points out, breaking its screen, button, sensors, or other various parts while doing any of these activities could be very expensive: repairs for the watch will cost $499 if you don’t have AppleCare Plus (we’ll get to that in a minute), according to an estimate tool on Apple’s website….