Systems, apparatuses, and methods for determining item availability are provided. A computer implemented method for determining item availability in a shopping space comprising: receiving a request for an item for purchase from a customer, querying an inventory database to determine whether the item for purchase is in stock, in an event that the item for purchase is not in stock according to the inventory database: determining an out of stock response to present to the customer, in an event that the item for purchase is in stock according the inventory database: instructing a motorized transport unit to travel to a display space in the shopping space corresponding to the item for the purchase, determining whether the item is available in the display space based on information captured by one or more sensors of the motorized transport unit, and in an event that the item for purchase is not available in the display space: determining an item unavailable response to present to the customer.