Imperia and Atlas machines are popular. Both roll pasta to a very thin thickness (a key feature). Both are solidly made from chromed stainless steel, no plastic parts. Both are made in Italy. Both cost about the same. I bought mine locally from an Italian grocery for @ $35 (might be a few $ more now).
I have owned my Imperia for many years with no problems or oxidation. Imperia sells a motor attachment seperately, though I can not attest to how well it works as I do not own one.
When cranking by hand I find that a helper is always useful as two hands never seem enough for me.
I haven't looked at these for years, but the ones I remember for home use had metal die and plastic housings. If you're thinking about a stainless steel housing, I think you're into commercial equipment. Or I could be all wet.
Kitchen Aid has an extruder. See this: http://chowhound.chow.com/topics/554747
I saw that some others appliances(Bosch mum 86 etc.) with pasta extruder as an accessory are made of bronze or metal. I have no concerns about stainless steel obviously, but I have some regarding those others two materials. I hard that they both oxydize with time so they release unhealthy substances on food. Is that true?
I got this one a week ago and so far am happy with it.
It is a manual and it is much easier with two people helping make it. It also makes it more family orientated to have more than one person doing all the work. I like this aspect of having someone to cook with.
It might be nice to have the machine attachment and I could probably do it on my own. This one is very stout and seems very solid and well built. It rolls the pasta out nicely and thins it to the desired thickness. Made in Italy.
The first batch was angel hair and the next was duck ravioli. There does seem a bit of getting used to how I fed the dough in to get a better end product. But that seemed quickly had.