What year was Sew Gem sewing machine model 215 manufactured?

I believe it was manufactured in 1950. My grandparents purchased one; we have the invoice dated September 19, 1950 from the company in Lincoln, Nebraska where they purchased it and also a letter confirming the sale of the machine and buttonholer dated September 25, 1950 from the company's home office in Omaha.

Do you know the approximate value of this machine? Thank you