I still have my first sewing machine, a Pfaff 262. It is an all metal, mechanical machine I bought brand new in 1968, and it is still the workhorse today as it was back then. Yes, I have modern, computerized machines as well, a Pfaff 2170 bought in 2008, and a Viking Epic embroidery machine.
These old mechanical machines come up on Craigslist and Green sheets and also at estate sales. Also eBay. Good luck on finding a good one for if you keep them oiled and don't let them sit idle over long periods, it will last for generations.