Include Individual Item Costs in Overdue Notices
Make it an option to also include the item cost in the overdue notice as well (incentive to return!).
In our date due slips (JasperSoft) we include the cost of each item and a total cost to show what the patron saved by using the library vs. buying.

The product team will review this idea for consideration for a future release.
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Robyn commented
I could be wrong but I had assumed this is what the merge tag {{item_total_owed}} did. Have you already tried that?
It may depend on your ILS configurations, but as long as your system has billed their account for the replacement cost of the item, I would think that's what would display when you add a merge tag for the amount owed for that item.