You've gotten some good advice. Gonna be real hard to get a value on an older accordion made by someone few know, especially without pictures. I recommend getting some good pictures, including close ups of the keyboard and the inside. Seeing the workmanship and the type of reeds will go a long way. Knowing the reeds are made in Italy does very little for Cajun music fans, but the exact brand may help desirability a lot.

But in the end, as was mentioned, any accordion made by any one other than a well know builder, will have a lot of understandable reservation among buyers who can't play it.