Answer:
First, he was never made a sacrifice... we know God stopped Abaraham before the knife came down. Second, to my surprise when I learned this last year, Isaac was between 36-38 years of age when this happened. We know this based on many scriptures that cross relate, but one being when they came back his mother Sarah had died. Since scripture tells us how old she was when Isaac was born, and how old when she died, it's pretty simple math.