Amazon Prime Day will be tempting, but shoppers may be better off waiting

An employee stacks items to be shipped at the fulfillment center in Phoenix, Arizona.
David Paul Morris | Bloomberg | Getty Images

As buzz builds for Amazon's second Prime Day sales event, a new report suggests shoppers may be better off waiting for Black Friday deals.

When comparing prices on 380 items across popular Black Friday categories including TVs and video games, the products cost an average 9 percent less on Black Friday than during Amazon's mid-July promotional push, according to analysis from Market Track.

All categories measured by the pricing intelligence firm, which also included laptops, small appliances and tablets, were cheaper on Black Friday. The biggest discrepancy was found in TVs, which were 15 percent cheaper, the research found.

"We were not shocked to find that Black Friday prices for top holiday products beat Prime Day prices, since they did not specifically say prices would be lower in the promotions of the event leading up to Prime Day," said Traci Gregorski, senior vice president of marketing at Market Track.

An Amazon spokeswoman did not immediately respond to CNBC's request for comment.

Last year's Prime event was the first of its kind for the website, drumming up excitement among shoppers during what's typically a slow month for retailers. After its inaugural event, which promised a greater number of deals than Black Friday, Amazon Prime Vice President Greg Greeley said it would "definitely be doing this again."

While many expect this year's sale to once again take place in mid-July, Amazon has been mum on the details. Some have speculated that the site could run two separate Prime Day events.

Even before Black Friday rolled around last year, the seller of everything from baby food to name-brand dresses came under fire for peddling items at lower prices in the days after the event. The small version of the Fitbit Charge HR, for example, was listed on Amazon for about $143 on Prime Day, including a $25 gift card on a future purchase. The following day, that same Fitbit was being sold on the site for about $117.

Shoppers were also disappointed by many of the products that were discounted on Prime Day, which skewed toward everyday or outdated items, including a chef's hat.

"Some deals will continue today on the few items that did not sell out," Amazon spokeswoman Julie Law said at the time. "In addition to offering our customers great value through Prime Day deals, we are working to always offer our customers low prices on all products, every day."

In any case, the event was a hit for the company. Amazon said it sold more products on Prime Day than its biggest Black Friday ever. It also had more new members try Prime worldwide than any day in its history — arguably the bigger win for the event.

Annual Prime memberships cost $99 a year, and encourage shoppers to make more of their purchases through the site. In April, the website started offering a monthly membership for $10.99.

"The goal of the event was multifaceted," Gregorski said. "Yes, Amazon succeeded in driving sales, but their focus was also to incentivize consumers to subscribe to a Prime membership."

As of March, Cowen and Co. analyst John Blackledge estimated about 44 million U.S. households subscribed to Prime, up 33 percent compared with the prior year.