You can typically find the PTA or whatever it's called different schools' budgets on their web sites. There are not going to be comparable apples-to-apples - but a general sense.
http://www.lafayettehsa.org/about-the-hsa/budget-activities/
The associations at different schools have different priorities and goals and things they pay for or need to pay for. (The Title I schools often have different needs that I would argue match having the higher per pupil resources... vs. it being the 'fair share'... but that's politics I guess. I wish all schools could get more per student).
It is a ridiculous way to rank schools vs. scores, culture, commutes, etc.