I think is a good idea to quickly see your min price you want to sell the craft for, especially if you are planning to sell it days after.
If an Item costs 161g in ah and I see profit of 18g, I need to go to the ah after the craft, remember the price, open profession tab and do the math.

It would be faster to just "print" the my cost there.

i dont quite get where u want to show it and what my cost should represent? crafting costs?

yes like somewhere here https://i.imgur.com/BVm4qyC.png, and yes crafting cost without going back to the AH and do the difference from AH price minus my average profit (to set it as min price into tsm auction operation for selling it later)