Guest Harry with the Wheatstone -

Chris Algar (Barleycorn Concertinas) is based in Stoke-on Trent, Staffordshire, and can give valuations based on
a) his knowledge of the range of conditions in which you can find instruments
b) contact with various suitably-skilled repair people, and knowledge of the cost of various repairs
c) awareness of the current market, supply and demand for the various concertina types

I have found people in the antique trade very hazy about musical instrument values. Most don't have any of the above knowledge, they don't see a wide range of instruments, and a poorly-described instrument offered in a general auction will never get the best price.

You would get some idea of the relative value (or at least replacement cost) of your instrument from browsing the Hobgoblin second-hand catalogue (http://www.hobgoblin.com/local/secondha.htm) (and also some clues as to how to describe the instrument appropriately). Bear in mind that a dealer will not offer anything like the "insurance" valuation - some valuers would give you two separate values, one for insurance (replacement) and the other for sale.

There are more people at concertina.net who may be able to help. The more info you can establish about your instrument, the better.

Ross