If you've not discovered cashback sites already you're in for a treat, here is a description:

When a customer makes a purchase online, instead of visiting the retailer directly, they may choose to go via a cashback website in order to generate a monetary reward for buying the products or services. The cashback website will receive a commission from the retailer and once the purchase, free trial, or information request is confirmed, that commission will be shared with the customer who made the purchase. This means that the cashback site makes a profit on the sale, free trial or information request and the consumer gets to recoup some of the initial outlay back or if they had a free trial or information request earn some money from it.