I have bought lots and lots of sewing machines at yard sales or on Craigslist. Everyone has given great advice. Although I have bought a couple of computerized Vikings and they have been fine. I figure if I pay 25.00 for a computerized machine and it only works for a few months, I have not lost too much. But I have never had that problem. You might want to get the persons word that they work and that they will take it back if you are not happy about it. I think looking for good brands is important. I would not pay 20 bucks for a machine I know only costs 100 or less at Walmart, if you know what I mean. Although I have picked up a few cheaper models that were new in the box for next to nothing. I usually make sure they are in good working order and then pass them on to someone that needs a machine.