Can you explain how you do this? Do you assign a number to each item upon purchasing?
Believe it or not, while I probably have one of the most extensive inventory "collections" in this group, I have no orderly inventory system in place. I basically memorize where I put everything.
I do something similar, but not packaged.
I assign a number to each item as I list them (serial number based on the date of listing). This gives me three things: peace of mind that I've picked the right item to ship, a really easy way to tell how long something has been active on Ebay, and easier tracking of sales since I use an Excel spreadsheet to track sales.