Depot Repair - How to track Finished Good Cost and Repair Item Cost

Scenario:

I have an Service organization where I stock batteries as well as service batteries.

Items that come in for service are not owned by the enterprise whereas the finished good item with the same item number as that of repair item are owned.

I should not consider the cost of customer item as an Inventory cost but it should be considered for the finished good inventory.

How to deal with such scenarios? How is this generally implemented when the 1. Selling and Service orgs are same 2. Selling and Service orgs are different.

Any white paper pointer will be of great help.