Since order would be shipped before invoicing, an alert at that time could be too late.

A client asked me if there was a way to be alerted if they take an order for an item where stock is insufficient for all orders in process. Although they can look at the available figure, the data entry person knows the item codes and processes orders so fast, she does not even have to look at the screen.
I created a GridView report, that refreshes automatically, that shows non-available items. At least the screen change might catch her eye.

I was wondering if there would be a way to set an alert when a definable condition is met, i.e. when item is placed on order and available is <=0, alert would sound. It would be similar to the alert that an item is not in stock at the location, but be based on the available number rather than stock quantity.

In Steve's example, the condition would be "for every item on the order stock at location is greater than qty ordered" [Okay to ship] OR "for any item on this order, stock at location is less than qty ordered" [Cannot ship complete]