The Houston area has 50+ charter schools, which receive the same amount of State money as public schools. The federal money does not follow the student. It started in 1995.
Some are good, some are okay, and some are terrible. Legally they must service low income students.
This has some good background on the issue, although it stops in 2001.
http://www.ncspe.org/publications_files/OP104.pdf
There aren't many charter schools I would send my child to, but a select few that have proven themselves and are more racially balanced. They all have entrance requirements btw. The ones that don't I would never send my child there.
The problem with school vouchers is the schools that pop up to service low income students face the same problems as the public schools unless they cherry pick students. If you have that, just open public magnet schools that can cherry pick like private schools. If you have attendance, grades, and behavior requirements any school will succeed.
I suggest alternative learning campuses for disruptive students, entrance requirement based magnets and charters, and gifted/special need campuses that allow students to work at their own pace. Also have GED programs for students in danger of dropping out, as well as half day work programs.