This is the fourth part of my tutorial on data pricing. Although the focus of this article is about pricing data products, we provide a brief review on pricing digital products here, since some general ideas in pricing digital products can be borrowed and extended to data products. In some cases, the boundary between digital products and data products is even blurry. We first discuss the three major streams of revenues for digital products. Then, we look at two major types of pricing models. The first is bundling and subscription, and the second is auctions. These pricing models are popularly adopted by digital product marketplaces.