7 On Your Side: Does Amazon's Prime Day really offer the best prices?

SAN FRANCISCO (KGO) -- Amazon's biggest sale of the year kicked off Monday night. 7 On Your Side's Michael Finney tells us if the much-hyped Prime Day really offers the best prices.

Jeffrey Lee of Tech Bargains scans Amazon for the best deals. He says some of the site's most popular branded items are on sale. "We're looking at users saving anywhere between $30 to $50 to $100 off the Amazon Echo, Amazon tablets and Amazon e-readers," he said.

Baby items, food and laundry detergent are also on sale. "That's kind of where Amazon is heading. They're trying to get people to buy more of their daily staples from them," Lee said.

MORE: How to save big on Prime Day

To qualify for this sale, you must be a Prime member, which costs $99 a year. Free 30-day trial memberships are available, but you must cancel to avoid automatically being moved into a paid membership.

Last year's Prime Day hit $525 million in sales, surpassing both Black Friday and Cyber Monday.

This year, big box retailers are countering with their own deals. "So Walmart is one of the biggest ones. We also know that Best Buy is currently right now trying to discount items lower than Amazon and Amazon is not price matching," Lee said.

Despite the aggressive push, the best prices aren't necessarily on Prime Day. Lee suggests checking price comparison websites like his own Tech Bargains, as well as CamelCamelCamel and Slick Deals for prices year round.

All of this is happening as more and more retailers are closing stores. Sears, Macy's and JC Penney are among those shutting many of its doors and struggling to compete against online competitors.

Business professor Kit Yarrow of Golden Gate University thinks retailers can withstand the Amazon onslaught with better parking and customer service, hassle-free shopping and returns, and by integrating technology in stores.

"They really want it to be fast and easy. What they love about going to malls and, in fact, consumers say they would actually prefer to go to malls. What they love is surprise and delight," Yarrow said.

With demand so high, Lee says Amazon customers can expect to wait six weeks or more for some items.