It used to be only hotels and airlines changed their prices several times a day.  But we found online retailers who sell common household items are also making adjustments throughout the day, especially for appliances and electronics.  While stores competing for your business are battling online, there are things you can do to get the best deal.

While shopping online recently, Amy Shoaff noticed prices for the same item on the same website changed substantially throughout the day.

“General everyday items fluctuating anywhere from $40 to $300,” she said.

Shoaff discovered a growing new trend.  Some retailers are changing their online prices hour by hour, and sometimes even minute by minute.

The goal is to have a product priced so it pops up as the lowest priced item in shopping search engines, or Amazon's coveted "Buy Box."  That's where most consumers look to find the best deals.

"It’s more a battle of getting the right screen position as opposed to trying to sell it as quickly as possible,” said Chris Buckingham with the Professional Pricing Society.

We worked with Decide.com to monitor prices on several items on a well known shopping website. 

First: an iPad.  At midnight, the iPad was $511.  At 6 a.m. it was $503.  By 7 a.m., the price sunk to $475, where it remained until 2:30 p.m., when it jumped to $510.  At 10 p.m., the iPad increased to a high of $529.  That's a total price difference of $54 on the same product on the same site -- all in one 24-hour period.

“The suppliers are constantly monitoring each other,” said Buckingham.

Decide.com's tracking software found the price of a particular brand of colored pencils ranged from a high of $3.32 to $2.22 over a 24-hour period.

With duct tape, in one day, the price ranged from a high of $7.83 to a low of $2.00.

“What has changed fundamentally in the past 12 months is the speed and scale at which prices are being set,” said Eric Best, CEO of Mercent.

Some retailers hire software companies, such as Mercent, to monitor the prices of its products and make changes based on its competitors.

“Because consumers now are researching their offline and online purchases in advance more than 50 percent of the time,” explained Best.

There are websites which will monitor prices for items you want and alert you when the prices drop or reaches an amount you'd be willing to pay.  For example, if you add an item to your Amazon shopping cart and leave it there, Amazon will notify you of price changes.

Showaff has a warning about clicking on the least expensive deal found on search engines, though.

"Free shipping, returns, make sure you’re using those things to your advantage because sometimes just price isn't always the cheapest," she said.

So which product prices fluctuate the most?  Decide.com says electronics, appliances, clothing, shoes, jewelry and even household staples like dust pans change in price the most often.

Some experts suggest if you ordered something from a retailer and the price dropped within a reasonable amount of time, contact the business and see if they'll refund you the difference.