Back at 7:40 now with "Gma on the money" and this morning we're helping you save on your holiday shopping. Almost half of all holiday shopping will be done online this year and ABC's Rebecca Jarvis is here with apps that guarantee we're going to get the best deals, Rebecca? We can guarantee you that, that's right. Good morning to you and the national retail federation estimates we will spend $105 billion this year shopping for the holidays online but with prices fluctuating as many as dozens, even hundreds of times a day, how can you make sure you're getting the very best deal? Take a look. It's the biggest sales season of the year. Here it comes. Reporter: But with holiday shopping comes fluctuating prices. Take a look. This hello Barbie doll on target.com was originally listed for $74. Then $69 and then $59 in just a few days. Yolanda says she buys most of her holiday gifts online and spent nearly $1,000 on her gifts last year and has her hands full this year with her family's wish list. I want an iPod and headphone. Laptop. Ps4. I get frustrated because a lot of the toys that are popular are the ones the kids want and the markup is insane. Reporter: Enter consumer savings expert Andrea wororc this. . She says use shop genius or invisible hand that run in the background while shopping online. If what you're about to buy is cheaper they'll alert you before you purchase. So I won't have to go to different sites. Exactly. It does all the work for you. Reporter: That laptop for her daughter we first found on Amazon for $330 but invisible hand found it on Best Buy for $279. That's amazing. Reporter: Next up electronics on your list? Name your own price with green toe. They negotiate with retailers for free. On green toe these beatsheadphones for Yolanda's husband once $99, now just 72 bucks. And that includes shipping and tax. That's incredible. Reporter: Finally did you know the savings don't have to stop once you've made your purchase? Websites like slice and brand-new paribus work to get you money back on stuff you've bought. Prices are changing. Hundreds of millions of types per day. With paribus, buy what you want, we'll take care of everything else. Reporter: If the price drops, you get me the refund? S that sea right. Reporter: They can scan all your sales receipts and if they find a better price elsewhere they'll file a claim for a refund. Paribus taking 25% of whatever savings they find you in all saving Yolanda and her family almost $300 for a happier holiday season. Two more great apps that saved her an additional $100, shopsavvy and redlaser scan the internet for sales so you get the lowest possible price when you buy. As for paristbus that gets you money back after your purchases, they say they don't see or store any of your personal information from your e-mails. But for a good idea create a separate e-mail just for those online purchases to link to the account which is just a great way to shop online in generally so you don't get all those e-mails. Amy is taking serious notes. Throughout that whole segment. Saved a lot of money. You did. Coming up, Patti Labelle's