Russ Roberts, who I agree with on most subjects, often contends that we are greatly disadvantaging poor children because the schools that they go to are awful.
I have to disagree with Russ on that subject. There are only an insignificant number of truly bad schools in the US (or good Government run schools for that matter.) What is fooling people is that there are some schools with a very good set of students and other schools with a very bad set of students. The former schools look good and latter look bad. I went for one year to one of the top rated Government high schools in the USA (Classical High school in Providence RI) and the teachers there were not very good. I also went to a school with a very bad reputation for 3 years and if anything the teachers there were a little better. My theory for that is because any teacher could survive with Classical's students the teachers were worse. My brothers who went to classical 4 years joked that it was the school for the mentally ill (pause) teachers.
On funding I think we have gone beyond what is a good level of funding and that most students go to school for longer than optimal. It would be nice if teachers eared more but most of the addition money spend by school departments in the last 40 years has gone to administration and that has served to make teachers lives more miserable (see: Considerations On Cost Disease More bosses?). BTW it is hard to pay people more than the market rate (see: Giving Away Money Costs More Than You Think) and some people are willing to teach for free (see: Arnold Kling, Steve Wozniak).
I think per student funding of schools should approximate what the median income family would spend on schooling if there were no Government schools.
I think you could theoretically achieve that by charging above median income families the full cost for each child that they send to the Government schools. Since that is a political non starter, I think that the way to go is to try to reduce school spend whenever possible.