Most shoppers are price sensitive and looking for good deals. If a price changes on a website and no one is notified, was the price change effective? There are various ways that retailers inform shoppers of price changes -- physical flyers, digital flyers, promotional e-mails, tweets, etc.. But most of these forms are general notices meant for the general public. Even promotional e-mails are probably formulated for different customer segments.
Does your favourite retailer communicate differently if prices have changed for items in the shopping cart, or saved for later, or in a wish list? When Amazon customers view their cart, Amazon looks for any price changes in their cart or items saved for later, and alerts them that prices have changed. This is a great way to see that there are discounts available now.
Frustrated Shopper Suggestion:
Understand which customer segments are more price sensitive than others and help them to understand when prices change on items. This suggestion is not to create a discount specifically for that shopper, but to inform that shopper of a price change that has been already made in general. If a price changes on a website and an interested customer is notified of the change, there is a better than good chance that notification will result in a sale!
That's all for now. Gotta go shopping!