Marion, if you are in the US and you itemize deductions, on your federal return, you might consider donating the guitar to Goodwill or the Salvation army, etc. That way you can set the value where you believe it fair and get a percentage of that from you tax deduction. Believing it to be worth $400 dollars is not the same as getting some one to pay that. I believe Rick's guess of $100 would be much more likely, if you could find a Classical Teacher who would sell it to a student and if that teacher though it to be superior to the new guitars. You've got until tax time to try and sell it for your price.
good luck, Fortunato