Inventory Stats and History Pro
This feature is available in PlainInventory Pro.
Keep track of current quantity, average cost and price, history of item movements.
Inventory Item Stats
There is a nice page showing various useful details about your inventory items performance. Go to Inventory, choose the item you are interested in, then click the Stats link in the menubar.
You will see the total number of purchased and sold items, and average prices for purchases and sales.
Inventory Item History
Similar to the status page, there is the inventory item history page that will show you all the movements of this item. You will see when it was added to sales or purchases, received or shipped.
Go to Inventory, choose the item you are interested in, then click the History link in the menubar.