I always check the serial numbers on the Singer site. Their charts will tell you the model, how many were in that batch, the date the serial numbers were released and the factory they were made at.
http://www.singerco.com/support/serial_numbers.html
Also, be careful it is says "runs" and not "sews". There is a difference. And make sure the bobbin case is included. Those go for about $45 each themselves.