My theory on the hand cranks is the older Enterprise units were cast and made in Pennsylvania for something like 75 years, and for the past 30 or 40 years the same units have been made in PA under the Chop Rite brand, which is still in business and selling these units new (along with parts). So that's almost 100 years of the same basic casting and design. Do a search and you can find the larger Chop Rite units priced on the sausage making sites for a couple hundred bucks. For a hand grinder! http://www.sausagesource.com/catalog/8b.html
I suspect the Porkert (something sexy about that name), Weston, along with Chop Rite are high quality units.
I'm guessing that many if not most of the other units sold by the various makers and places (especially the cheap new units found on Ebay) are going to be cast in China and unless made from stainless are going to be tinned. Chop Rite told me they can no longer "tin" a grinder in the US. They are now Teflon coated. But the big factor will be quality and fit of the blades and plates. On high quality units, they are high carbon hardened steel or stainless and mated to a tight fit. The wear point is the down stream side of the plate holes. Meat is pushed into the hole, where the blade shears it off....the back side of the hole in the plate erodes and elongates over time (grinding spices with the meat probably speeds this process along). Once that elongates and rounds over, it won't cut much. Good quality plates hold up better. I tried sharpening an Enterprise knife and couldn't hardly touch it. The same could not be said for a cheap replacement blade I got as an extra with one unit.
So if I'm patient, for less than $30 I can get one of the best hand grinders ever made. Ebay is the place to look. You will find 100 food choppers in antique stores for every Enterprise, and I've never seen a decent Enterprise in an Antique store. Rough ones are priced at $40 and up.
If you are only going to do a little, look for an Enterprise #5 clamp on. I've seen those new in the box sell on Ebay. They will grind 5# of sausage in much less time that it took me to type this.