I know that Nout had one a few years ago.
Maybe he can tell us something.

There's one currently for sale on Elderly Instruments' website:
http://www.elderly.com/vintage/items/160U-533.htm

And hugely overpriced.

They are still built new by Zero Sette in Italy, very expensive there, and IMHO not worth more than a souped up Cajun King. See: http://www.accordionsoflondon.com/index.php?page=shop.product_details&flypage=shop.flypage2&product_id=214&category_id=17&manufacturer_id=0&option=com_virtuemart&Itemid=26. A fair price for an oldie if in good condition would be some 700 to 800 dollars ... advice from a person well familiar with those melodeons by trade. - Nout

That's $2,327 USD new delivered in UK!

20% of that is Tax... making it around $1900 USD.

Depends on the mechanisms and the quality of the reeds, tone and playability as to what it is worth.

A Castagnari is around the same price.

I would think the box on Elderly's site is worth $850.

Be wary of Elderly's descriptions. I have had three unfortunate experiences with their used accordeons.. all because of incorrect descriptions.

It looks like it is on consignment, so I guess they are using the sellers description.

The description is typical of Elderly with some obvious input from the seller.