Ability to change the order of the line items on a Purchase Order

This would be helpful when having multiple items on a PO that have tiered pricing from the manufacture. Example: Ordering custom gobos from Rosco. The first one you order is one price and any copy of that (a different item number for copies) is a lower price. Right now the PO section seems to put items in alphabetical order which separates the two items in the PO list.