People don't understand the value they're getting with the old sewing machines. Also, most people just don't sew.
Why would you spend $150 if you can buy a new one for 120 and it has multiple stitches. Besides you might use it 5 times in the next 10 years.
It doesn't make sense until you realize the new ones are so cheap you can't use them more than a couple of times.
There a reason whey people used to spend ~$2000 in today's money for a sewing machine.