You won't get back taxes, storage, shipping, handling and postage charges on what you buy, and "Coverage is limited to three of an identical item with a limit of one refund per eligible item." Got that?
According to the AmEx website, if you change your mind about an eligible purchase made with an
card for any reason, you can return the item within 90 days and AmEx should normally refund you the full cost, whether or not the retailer wants to accept the item. Presumably, your actions must be reasonable, and it's unlikely you'll be able to return under this program that $250 bottle of imported Champagne you bought to celebrate Romney's victory and then downed to drown your sorrows. You only stand to get up to "$300 per eligible item, excluding shipping and handling, up to $1,000 annually per Card account," according to the company's website.
This isn't price protection as such, but it may give you some leverage if you want to renegotiate with a retailer.
Chase credit cards
A search on the Chase website revealed no entries about price protection. However, an email reply was received after an inquiry was sent to the marketing department:
"We do offer price protection benefits provided by MasterCard and Visa, but these benefits vary by card. Customers who are interested in this benefit and others are encouraged to contact us to learn more."
So, if you have a Chase card, or are thinking of applying for one, call the company's call center to discover what, if any, price protection you stand to receive.