You can get an apple grinder like the one in the DIY article, without having to make one yourself. I have a friend who bought something similar and it works great. I'm not sure where he bought it. A couple people can grind and press 50 gallon of juice in an afternoon. It goes faster with friends. I also know a guy who uses a garbage disposal mounted on a small metal sink that serves as the feed and a frame so the whole thing sits on top of a press bucket.
Last weekend I met a guy from England who helps his friends scrump apples and they use a woodchipper, then ferment the juice in barrels. That would take a serious pile of apples.