Abstract: The disclosed technology provides a method for granting partial refunds (post-payment discounts) to purchasers of a product only if a pre-determined/pre-defined number of sales has been met to purchasers signing up to be part of a partial-refund program for the product. In this manner, the purchasers have the incentive to spread information about the partial refund to their friends, such as via social networking, and “advertising” on the part of the seller, who then makes more sales. If the sales threshold is met, the partial refund is issued.