My Supermarket is a website that can help you answer that question.
"We work for the consumer to find the best price online for the items that they're buying every day," explains MySupermarket's Suzanne Kuhl.
Not only does MySupermarket let you comparison shop for non-perishables at multiple online stores, including Walmart, Amazon and Drugstore.com, it will also help you find better prices, if you pick an item that's not the best deal. It's a feature they call "Swap and Save."
Kuhl says, "Essentially, it's someone watching your back while you shop. We try to design a store that makes it very easy for you to spot the best price, but sometimes you might miss it. So, if you add a 12-ounce container of Heinz ketuchup and we actually found a 24-ounce that's cheaper that you might've missed, we'll prompt you to Swap and Save to get the better price per unit."
The site will also suggest comparable brands, if items are similar.
"Sometimes, you're going to be very loyal about a product and not willing to switch," Kuhl explains. "Other times, you may not care if you get Colgate or Crest. You just want to get the better price."
Finally, MySupermarket helps you save on shipping. They call it "optimizing your cart." The site figures out whether you should switch from one retailer to the next, so that you pay little or nothing for shipping.
Kuhl adds, "If you've spent over $75 and we don't find a way to eliminate all the shipping fees, we will reimburse you for any shipping fees you have to pay to the retailer."
To check out MySupermarket.com, click here.