Don't make the easy mistake of assuming that school spending is correlated with educational outcomes, there is plenty of evidence that that's not the case. I would suspect that the biggest reasons why educational outcomes tend to be correlated with the income of the school district have to do with culture, parental involvement, and educational levels of the parents. If you grow up in a house of educated folks you are more likely to value education and put effort into it, and you are more likely to be held to a higher standard of achievement in education, regardless of the quality of the education you get.
What are "cheap schools" today are outrageously expensive by the standards when I was young.
The issue here is not whether a second or third tier school can give a decent education, it is whether poor families see school as an option at all. When you combine skyrocketing costs with growing numbers of horror stories of people who are financially destroyed, and cannot even (as when I was young) declare bankruptcy, more and more are going to make the economic decision that they cannot afford higher education.
