A good quality machine will last for years, the cheap machines won't. You really need to spend at least $300-400 to get a decent machine. There's nothing worse than a machine that doesn't work properly. The older machines that are all metal are really good and sew well. New Singers are only the name, not the quality that Singer used to be known for, very sad in my opinion. I own and use the wonderful Singers from the past. Viking makes good machines, the Emerald line is very good, #116 is good starter machine.
Getting off my soapbox now.