Human cost shouldn't be too tricky to guesstimate.

An average US person produces about $142k/year (85k in gdp, divided by 60 % of working age), killed with about 40 years of productive life left is about $5,6 million. Add to that the lowered productivity of the close relations due to grieving and change of circumstance, as well as societal loss of morale, and you're probably looking at a loss of production of just under $6 million/life. And fractions of that depending on disability for non dead casualties (e.g. PTSD or loss of limb might be 50% depending)

The Iranian equivalent is about $400k/life, or less as civilian casualties tend to be older than prime age soldiers.

Now calculating the US cost of loss of Iranian civilian lives would be more challenging (loss of standing, loss of morale, loss of legitimacy, and follow-on actions of instability and discontent).