I have a singer sewing machine model # 221 serial #4518 there is a 3 on the machine D10669 says it is nw 32.8 pounds and gw 35.9 pounds box is from sears. The sewing machine sets on a wooden(cardboard) base. Can you tell me what it's worth or where to sell it? It is electric.

Without a picture its hard to tell. The nicest average mint condition ones start at around $150.]
You can try putting the serial number in this site or calling them
http://www.singerco.com/support/machine-serial-numbers