Update GetItemCost to return the total invested even if you have none of that item left. If you sell all of an item but are waiting for the mail to arrive, you can still see how much you have invested even though you don't actually own any more of that item.

<Ui xmlns="http://www.blizzard.com/wow/ui/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.blizzard.com/wow/ui/
..\FrameXML\UI.xsd">
	<Script file="AceEvent-3.0.lua"/>
</Ui>