​Why it's "buyer beware" on Black Friday

Consumers are increasingly skeptical about whether they're going to find great values on Black Friday, and a new study finds that there's something behind those hunches.

One-third of items for sale on Black Friday will provide no savings to consumers, WalletHub found in an analysis of thousands of items sold at retailers, including Amazon.com (AMZN), Costco (COST), and others. One retailer stood out for its lack of Black Friday discounts, said spokeswoman Jill Gonzalez.

"When we look at the items that will be more expensive on Black Friday, Amazon is the worst offender," Gonzalez said. "We've seen that with Amazon, it's actually the earlier the better" when it comes to buying gifts.

Amazon took issue with the report. "The study did not use our correct Black Friday prices. It is simply wrong," a spokeswoman wrote in an emailed statement.

Other reports have found that Amazon offers significant discounts, such as one September study from Boomerang Commerce that found Amazon "competes very aggressively" on consumer electronics products, with an average discount of 66 percent off retail prices. WalletHub noted that Amazon did not provide all the requested data for their Black Friday prices and wasn't able to include all deals in its analysis.

There may be a shift in how both consumers and retailers view Black Friday, which earned its name because the influx in shoppers on the day after Thanksgiving traditionally pushed retailers into the black. But a majority of shoppers have already started their holiday shopping long before Thanksgiving, according to the National Retail Federation.

Pity the parent who wants to buy a Playmation Marvel Avengers Starter Pack Repulsor toy for their child on Black Friday from Amazon.com. According to WalletPop's analysis, the toy will cost $114.25 on Black Friday, or $44.26 above its pre-Black Friday price. Overall, about 17 percent of items will be more expensive on Black Friday than they are currently listed for on Amazon.com, the study found.

"I was a little shocked by the Amazon numbers," Gonzalez said. "I'm a Prime member, and I love Amazon, and I assume I'm getting the best prices."

The best Black Friday discounts will be found at J.C. Penney, where the average discount will be 68 percent, followed by Kohl's, where the average discount will be 67 percent, WalletHub found in a separate study.

Some types of items will provide better values than others on Black Friday. Books, movies and music will have an overall additional discount of 28 percent on Nov. 27, followed by 22 percent for video games and toys. Furniture and jewelry will only provide an 8 percent and 4 percent additional discount on Black Friday, the survey found.

Almost two-thirds of consumers surveyed by BestBlackFriday.com said they don't believe Black Friday offers the lowest deals of the year. That shows that consumers are "catching on," Gonzalez said.