Assuming that you're buying a used machine, one way to get an idea is by weight -- generally the better machines are heavy because they use all metal constructi

Assuming that you're buying a used machine, one way to get an idea is by weight -- generally the better machines are heavy because they use all metal construction. Also you can get an idea by going by feel -- do the various mechanisms feel smooth when used? But, in general, google is your friend when it comes to choosing specific models. I usually see great used sewing machines at swap meets, garage sales, and thrift stores, so that's what I'd recommend. I'm sure there are others that can give better advice. Maybe some relatives have a sewing machine stashed away somewhere? Local sewing groups?