If you are looking for a good machine I would suggest one that is used from a good dealer. They are all gone thru and should work well. I suggest an older one like this one. They are all metal, not the plastic that so many of the inexpensive ones have today. Here is a picture of one on Ebay.
http://cgi.ebay.com/Kenmore-Sewing-Machine-Model-158-15251_W0QQitemZ330254149384QQcmdZViewItem?hash=ite m330254149384&_trksid=p3286.m14.l1318
I would consider a Kenmore or a White from this era.
Debbie