Around here I have found that at garage sales people want too much money so I have quit going to them. They usually want to sell it close to what I can find it at retail. At that point I would rather buy it new and get the warranty.
I have found one local consignment store here that I can usually get awesome deals on stuff. Like they have $30 Stamping Up sets for under $10. At a garage sale the same sets would be $25 or even $30.