The InventoryItem resource now includes a cost property
API
Effective October 25, 2018
Product cost lets merchants record the unit cost of their variants, track margin, and report on product performance within Shopify. This feature will roll out to all stores over the next few days.
Merchants will see a new cost per item field when editing variant pricing and will be able to bulk update this cost via the product CSV importer and the product bulk editor. There will also be changes to analytics, including the addition of new Profit Margin, Cost of Goods, and Gross Profit reports.
To enable our partners to leverage this feature in their apps, we are exposing a new cost property on the InventoryItem resource. To learn more, see InventoryItem.