One computer-implemented method comprises receiving requests to create subforms associated with a digitally stored expense trip preapproval form; in a particular subform, receiving input specifying input values for attributes of the particular subform, the plurality of input values collectively specifying the travel expense item; programmatically transmitting, to a price modeling server, a query comprising the input values and requesting a cost value for a travel item corresponding to the input values, and receiving a predicted cost of the travel expense item; automatically updating the particular subform to display the predicted cost and to populate the predicted cost into a total cost attribute, the total cost attribute being separate from the predicted cost; receiving an updated value of the total cost attribute and updating it; in response to determining that the updated total cost attribute differs from the predicted cost, presenting a notification specifying an amount of the difference.