If you frequently shop online you should check out PriceProtectr. The site is really easy to use. You simply copy and paste the URL of the item you purchased at one of 162 online stores into their online form. Enter your email address, (they promise not to spam you), and you’ll receive notification if the price drops within a specified number of days. (The length of time depends on store policies.)
I recently purchased a number of items at Macy’s that dropped in price within the ten day protection period. I received an email nine days after my initial purchase, letting me know that the prices had fallen. The notification even included the number at Macy’s to call for price adjustments.
I called Macy’s, asked for the price adjustment, and received a credit on my account within fifteen minutes of receiving the email!