There always has been and always will be a market for sewing machines, even vintage and antique ones. Some are valuable now, some not so much but as the decades pass and more are gone, eventually even ones that are still common now will become more valuable because there will be fewer of them. Someday, and it will be a sad day, the last cast iron sewing machine in the wild will be gone. There's value in an old Buick, I know it cost me a pretty penny when I hit one years ago. Even Edsels and Touch N Sews have a following.
Cari