Hardly anybody will take used machines on trade anymore. They can't sell them for much, and anyone they sell the used machine to would have been a candidate to have bought a new machine at a higher profit margin.
And if anyone complains about the profit margin of a sewing machine dealer, consider that your restaurant food costs only about 25-33% of your price. I don't hear anyone complaining horridly about the profit of restaurants though. Buildings, staff, utilities, all the "free" classes, training for staff - there are lots of costs that are not always obvious.
Pam