This suggestion is to add a new sort category called "Equipped" to the buy menu accessible from the base purchasing screen. "Equipped" means any item currently loaded onto a dropship or any other craft, this sort option is already tracked for individual craft, so you would only need to add together all of the "equipped" sorts from every craft in service to determine what is currently being used.
The use case is very common, as a player I often need to (re)purchase equipment multiple times a month, especially consumables such as grenades, medical supplies and ammunition. This would give me a way to quickly shorten the list of purchasable equipment to only those items which I am already using.
