Hi Justin,
This shoud be part of the stock estimate templates in the report designer. I suggest looking at the cost field of your template and the "Before Print" label script. See below:
You should have a script that takes the "Amount" field and divides it by the quantity. That would give you the Sales price and put that value in the Cost field. My feeling is that you're likely missing this script on your report.
Hope this helps.
Adam