One thing to remember here is that the public vs. private debate is not an all or nothing proposal. You don't have to commit to either 13 years of one or 13 years of the other. I started kindergarten in a public school and stayed there until second grade, when we moved to a city that had bad public education. In fifth grade, we moved again, this time to a wealthy district, but one whose elementary education was only geared for the "lowest common denominator". By seventh grade, I'd reentered public education, and stayed there until the end of my undergrad studies.

Yes, it's expensive, but when the alternative just isn't feasible, it may be best to consider all the alternatives, one year at a time. From my experience in the schools I went to, "Are you coming back next year?" was a very common question.