"The rate and review feature lets consumers post comments about products online. Since the July launch, consumers have written and posted reviews on 80,000 products, with more than 1,000 coming in daily.

"About 80% of items have either a four or five star rating, which gives us confidence we're selling quality merchandise," Vazquez says. "When the service first launched, the suppliers got a little nervous, but even products that get one-or-two star ratings provide useful information and feedback from customers."