One day something you want is half-price, the next day it's full-price.

You literally have to check Amazon every day to never miss a bargain, but an app called "Amazon Alert" will do that shopping for you.

Let's say you want one of the popular Bamboo Pillows. You can order it now of course, but if you're willing to wait for a sale, the Amazon Alert app will notify you of a price drop.

It works several ways.

With the free version you shop Amazon within the app.

You'll need to enter the product name to search for it.

I'd recommend doing the window shopping on the Amazon website.

The paid version, which is $4 for a year, will import your wish list you have saved on Amazon.com.

You can also use Amazon's share button on an item to have it sent to the app.

Once you have the item saved in the Amazon Alert app, you name your price and if the item goes on sale for that price, you'll get a notification by e-mail so you don't miss it.

Obviously this app isn't good for items you want right away.

But if you can wait until it goes on sale, Amazon Alert will save you more than the $4 it costs.

You can find "Amazon Alert" on iTunes or Android.