Sell gift cards securely from Sleep Number with Raise's online gift card marketplace. Your Sleep Number gift card will be listed in front of the thousands of buyers perusing our gift card exchange. To sell Sleep Number gift cards quickly, set the price between 2% and 20% off the original amount. The asking price is up to you, but it really depends on the popularity of Sleep Number gift cards. Remember, you can adjust the selling price of your gift card at any time.