I have a Singer Sewing Machine model 400w21..it is a Century Edition...industrial with one of those typical green tables/motor attached type....someone is interested in buying it and I have no idea what they are worth..does anyone know, or know of someone who can give me a good idea...

It is a great machine, no reverse, about 5000 stitches per minute, runs beautifully, grey in colour...and sews an amazing stitch...

What would be a fair price to ask?

i sold mine for a 100 it had a reverse

You can check eBay to get a ballpark idea. Use "completed listings" to make sure that they actually sold.

From what I have seen, there is little demand locally for industrial machines for home use. I think that most machines like that sell in my area for $100 to $150.