Uhhh, I think you miss the point.   The 40 million is the projected cost of building the school.   You suggested that it works out to 53 thousand per student, which it would be if only 750 students used the school.   However, because of constant turnover with students moving on to middle school, much more than 750 students would be served by the school.   Any other costs are beside the point.   

Besides, if your point is the cost, have you considered the footprint cost per square foot of the school, per student, as opposed to a school built on a sprawling campus in the middle of town?