I think many of us in the forum become kind of suspicious when an accordion that has sat unplayed in a basement for 40 years is assessed as being in great shape. I’m not saying it couldn’t be, but usually the way an accordions performance degrades over time it can be hard to quantify without comparison with a properly working unit. The valving drys out and stops sealing correctly, the reed wax that holds the reeds in drys out and becomes brittle (meaning one bumpy car ride or spirited playing can dislodge any number of the 130 reeds in this accordion), and reeds slowly go out of tune.
This example would’ve been built for Titano by Victoria. The specific year it was built is of much less importance to its value than its playing condition. Because there are so many reeds in an accordion, when it is due for service, the bench time can add up as each reed can need attention. This makes it so some perceived minor performance issues can cost more to repair than the instrument would be worth after the repair. I would say as a private seller selling this “as is” $100 to $300 is about the range I would expect. Someone might point out accordion shops will have the same model for more than twice that, and that’s true but they are selling the instrument after being serviced and with a warranty.