Between my wife and I, we have had several pairs of glasses made in Argentina with no problems.
The trick is- dont buy imported frames- like all other imports, they are ridiculously expensive.
Locally made stuff is quite reasonable.
I am wearing a pair right now of New/Old frames- they are a 60's design and mold, being remade today. I think I paid about 250 pesos for the frames. Industria Argentina. Similar frames in the USA are triple at my local optometrist in Bellingham Wa.
Single vision lenses are quite reasonable in Argentina as well. I had a pair of old frames I brought with me and had new sunglasses lenses put in by my local eyeglasses shop on Billinghurst, 150 pesos for lenses only.
But what is very expensive in Argentina are progressive bifocals. Those are cheaper in the USA.
I have heard two different stories as to why- one is that there is no machine at all in Argentina, and they send them to Brazil, and the other is that they must go to only one company in Argentina, which has the monopoly and knows it- either way, they are expensive.