at some point Italian becomes vague with Bianchi made in Mexico and later Taiwan.
Both scarcity and value come from small hand-brazing shops, especially if it was likely The Actual Guy with his hands on it.
DeRosa, CIOCC, etc.
Marketing and importing also affect apparent scarcity. There are a lot of Mosers in Europe, but relatively few here, since there has been only one US importer.