To enable this, create a smart collection named All Products and set the condition to 'Product price is greater than 0'. You can create a collection through the 'Collections' menu in Shopify admin. Or you can turn this section off through theme settings.
The Merc with a Mouth is now a POP! Pen! Contains the complete set of all 3 pens: Red Deadpool, Gray X-Force Deadpool and Black Costume Deadpool.