Free: Contests & Raffles.
I have the kitchenaid attachment and will say that I'D rather used a hand grinder. That thing is not designed to grind more than one meal worth.
quad: one thing I can tell you is that the 3/4 HP, which I have, lacks the "reverse" setting for the motor. But I'm not sure why anyone would ever need anything other than "forward." I would buy whatever you can find on sale or at a comfortable price point. If I my house burns down tomorrow and I see a 1/2HP model on sale, I wouldn't necessarily rush out and pay full price for the 3/4.