Hello, first time poster, short time lurker

I just acquired a used accordion and want to take it in to have it appraised and possibly sell. Before I do that though, I'd like to go in having some basic knowledge.
The accordion is a Stradavox. I think it's a Brevetto? It has 41 keys and 120 buttons and six sound thingies. You can tell I don't know a whole lot. I have attached a bunch of pictures which should help. From what I can tell, it functions as it should, the bellows are tight, all of the keys work, etc.
Basically I'm wondering if any of you knowledgeable people know where I could take it in the Chicago area and could get me a basic idea of what type of accordion along with a ball park price range that similar ones may sell for.
Thanks!
-d