Where can one sell an accordion and what is it worth?
The short answer for where to sell an accordion is almost anywhere. If you plan to sell your accordion in your vicinity, place an add in the "For Sale" Musical Instruments" in the Classified Ads of your local newspaper. Be certain to provide a price, a description of the accordion (length of right-hand keyboard and number of bass buttons), number of register changes on both the right- and left-hand sides and a general description of the instrument's condition and age, if known. Do not provide an address, but, rather, a telephone number or an email address for interested parties to contact you.
If you plan to advertise in a national market, E-bay is undoubtedly where you will want to place your instrument. You provide a digital picture and indicate the lowest bid you will be willing to accept. Bids are typically open for one week.
In order to determine the value of the instrument, follow this link for useful information.