Well your math needs work too... if the school has 4200 students and is K-12 and is in operation for 12 years the number of “different” students would only be 8050 [4200 +(11*350)]. It would have to be in operation 13 years to reach the 8400 level. But given that... the cost of per child over the 13 year period would still be almost $69,000. This is also assuming there is no maintenance to the building.
Overall the point is that in budget strapped times how in the heck do we justify spending like this on public facilities of any kind?
Like I said, it’s an atrocious amount of money, in any case.