The sluggish economy combined with a lively gold market means big business for companies that urge consumers to sell their old gold.

We've all seen the ads for the company that bills itself as the number one gold buyer in the country, Cash4Gold.

Last year, "Good Morning America" tested Cash4Gold and two other gold-buying companies by sending in packets of gold that a certified gemologist appraiser said could receive optimum offers of about $350.