Sorry Magi but I still think 10,000 records in a combo box is way too many. I think you should rethink the whole structure of the problem and your solution.
Can your items be categorized? By date? By alphabet? By Department? Can you develop relationships? e.g. Instead of creating a listbox or combobox of all inventory items. First have the users select from equipment type, then by equipment subtype and lastly the equipment. So the user may first select Pipe and equipment type, then Hardened Steel and lastly 24 inch. If one doesn't have that kind of narrowing down, you will really cheese off your users as they could be looking through literally thousands of entries.
Hope this helps,
Rewdee