Conn-Selmer has published s/n info. here: www.conn-selmer.com/content/resources/serialno.php M64054 appears to be mfg. in 1969. that's with a lower case "m" prefix. However, if its upper case and above the 5 digits, that would seem to be from 1921, in the "Wonder" series. See also www.saxgourmet.com/VINTAGE_SAXOPHONE_VALUE_GUIDE.htm Sorry I can't help with valuation. Those who can, however, will need considerably more info. to make a reasonable range estimate.