I gathered some data from Samara public schools about their non-budgetary income, i.e. money from charities, grants, and earnings from paid services. The X axe is for scores and the Y axe is for money. The circles are bigger for school that had pupils with max scores - 100 points for the unified state exam. I used this datum as square area and calculated the radiuses. So depending on this chart you as a parent can choose the school that has good results and affordable for you.