it's really not worth anything more than a student Yamaha at that serial#. That horn was produced in the early 1980's -long after the Selmer buyout which ended up in the gradual decline and value of the 400 line. The 400 line's antique value depriciates drastically after the discontinuation of the TopHat model, and takes another large hit after the Selmer buyout in 63'. It's value furthr erodes as it loses it's underslung neck, gold-plated nortons springs, and snap in resonators as the line continutes it's life into the 70's. Your Buescher may be a killer horn for all we know, but how a horn plays generally does not have a tremendous effect on the value of an instrument.