Ask yourself "Am I going to try to sell this item again anywhere?" - it could be on Amazon, in a different condition, on another marketplace like eBay... anywhere
If the answer is YES, you will want to mark the item as Sellable under the Refunds section of the Accounting tab
When you mark a refund as Sellable in Accounting>Refunds, we will provide a Cost/Unit Credit to offset the Cost/Unit captured in the original sale in your Cost of Goods Sold line of the Profit & Loss Report.
When your item sells again, the Cost/Unit will be captured in the second transaction if sold through Amazon again.
If did not make the change to Sellable, but still resold it, you would end up duplicating your total Cost of Goods Sold for that item because your Cost/Unit would be accounted for in both the first and second sale.
Should you sell the item again on a marketplace other than Amazon, you would simply account for the Cost of Goods Sold the same way you would for any other item you sell on that other marketplace (Tip: You can manually add Other Income and Other Expenses into InventoryLab)