Can you post the listing? Appraisals are a difficult thing. Too many variables. We can at least tell you if we think the price is in the ballpark though. Also keep in mind not every machine needs to be a steal. Sometimes a machine is worth a little extra just because you love it. There's also the fact that you have to pay a pretty hefty price for a new machine that even comes close to the quality of a good vintage machine.
The Singer 201 is considered to be one of the finest machines Singer ever made and is one of the few domestic machines that is actually suitable for commercial work. It would be a great piecing machine.
Rodney