Expedited checkout system through portable checkout units

A non-transitory, computer-readable medium comprising instructions that, when executed by a processor, cause the processor to:

• receive, at a portable checkout unit, an item identifier identifying an item sold by a store;
• transmit, from the portable checkout unit, the item identifier to a mobile device belonging to a customer of the store, the mobile device including a client application associated with the store that facilitates communication between the portable checkout unit and the mobile device, the client application on the mobile device being configured to:
• store, at the mobile device, an item element for the item received from the portable checkout unit within a virtual shopping list of items to be purchased by the customer, the item element comprising the item identifier and a count of items associated with an item type of the item;
• receive, at the mobile device, a selection from the customer to checkout from the store;
• and
• responsive to receiving the selection from the customer, initiate a checkout transaction between the customer and the store via the client application to purchase the items in the virtual shopping list from the mobile device.