Nowadays, perhaps the most prominent example of this sort of pricing can be seen in the airline industry.
Optional product pricing occurs when a main product is sold along with some accessories. The main product can be sold at a relatively low base price, but the firm can still get higher profits by selling expensive options to go with the basic product.
The airline industry today does this a great deal. There is the basic product, the flight. Passengers can then buy other products as add-ons to the basic product. For example, passengers can pay to check a bag or bags. They can pay for snacks. They can pay to reserve an aisle seat or a window seat. All of these are options that are tacked on to the basic product that is being sold.