If you can find one of the old metal Kitchen Aid models they are great (but pricy as they are scarce). Every now and then someone gets a steal of a deal on one on EBay, but I was never that lucky. If you can't find a good used one at a decent price, don't think on it too long, just buy it.
An alternative would be the Chef's Choice stainless steel model that is supposed to fit the Kitchen Aid machines. I've never used it but it looks promising in a google search. Runs about $100 bucks online with 3 grinding plates. Would post a link, but I'm pretty sure the selling store is not a forum sponsor.