The featherweights are too tiny to do FMQ. Look on the machines to see if you can drop the feed dogs. I saw a machine here at a yard sale that looked like it was from the 60's, the cabinet looked very nice. I already have 9 machines so I kept driving, but I sure wanted to go back!
I would think that if you are willing to go used you should be looking at less than $100. I would then take it to have professionally cleaned and have a tune up, after that you should be able to take care of it yourself.