I asked the same question a few mths ago and got so many positive answers I went out and bought 4 Vintage machines in a 4 wk period. My first find a Black 1951 Singer 301 at a tag sale for 30.00...Then a 1910 Singer Redeye on ebay for 55.00, Elan Grasshopper from the 30's 85.00, and finally a two tone 301A 1953 in cabinet 110...All work wonderful and I don't regret it and use all them for sewing and quilting.
They said the sound was wonderful, they purr, they do and you can't beat the straight stitch...they were right...And that's how they convinced me to go looking.
OH and to top it off I have my Grandmothers 1949 3/4 Singer model in cabinet that I never appreciated prior to joining this site and she's being rehabed at this very moment.