I've got a couple of sets of these screw on deflaters. You get four of them and they screw together to become one small unit, about the size of a cigarette. These cost $10 at most 4x4 shops. They're anodized aluminum and come in different colors.
They simply screw on and start deflating your tires. Unlike the Stauns, they don't stop -- eventually, they will deflate your tires completely, if you leave them on.
But they are still way better than kneeling and deflating each tire individually. You can do all 4 tires at once, and then walk around the vehicle with a tire gauge to see where you're at. You can check the pressure without taking them off. Once you're down to 10 lbs (or whatever), you simply unscrew 'em and replace the valve stem caps.
They work great, and the price is right.