(CBS NEWS) -- Amazon's (AMZN) giant annual Prime Day sale is here, and by now it's practically synonymous for bargains in online shopping. But does the e-commerce juggernaut always have the best deals? That depends.

According to an analysis done for CBS MoneyWatch by retail technology firm Boomerang Commerce, of the 100 top-selling toys and games, electronics, and home and kitchen products on Amazon, the Seattle-based company enjoys an advantage over its closest rival Walmart (WMT). Boomerang found that Walmart's prices are on average 35 percent higher than Amazon's in toys and games and 20 percent more in home and kitchen.

Target (TGT) is 2 percent more expensive than Amazon in toys and games and 11 percent higher in home and kitchen, according to Boomerang.

When it comes to electronics, all three were nearly even when it comes to price. Target is 5 percent is more expensive in electronics than Amazon, while Best Buy (BBY) was on average 2 percent higher. Walmart was on average 3 percent less than Amazon. On big-ticket items like consumer electronics, retailers often will match rivals' prices.

"If you're a shopper buying a pretty common item, on average Amazon is still going to be the cheapest. But if you're buying something that's a lot more niche, then you might need to shop around," said Michelle Ai, marketing manager at Boomerang.

Some of the disparity in prices between Amazon and its rivals can be explained by the numbers of products independent retailers sell on the site. But even when those sales are stripped away, Amazon's prices remain competitive, according to Ai. Target and Best Buy don't use third-party sellers on their sites.

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