Funding public schools the private way

A huge problem with public education is it is often simply underfunded. Many who claim this is not the case will probably say "but the U.S. spends more on education as a portion of GDP than any other country in the world!" To which I would suggest simply replying with, "and your point?" You can bet the person who just thought they made an argument probably won't have any idea what is considered "educational spending" by government accounting standards.
More importantly they probably don't know what "portion of GDP means as a result of having come up through America's educational system.  Where is the proof that this amount measured in proportion to GDP is somehow an adequate amount?  This is all pointless though, because the results are in, and it is clear. However, much money has been put into education... well there needs to be a lot more!
Just how much is needed? No one as of yet has created a model proportioning stupidity with the GDP, so no one really has any idea, but you better believe it's a lot!
THe problem is most states and the federal government has been battling a recession for almost the better part of  a decade and are now standing with nearly depleted treasuries holding just enough for their expense accounts.
But relax, no one need fear for their comped steak dinners or their child's futures. Believe I have found a long term solution to this revenue problem that should make everyone happy.
The idea is simple; parents of students can pay for grades. This is the model used by the ivy league schools. It is called grade inflation. The school wants to appear to have only the best and brightest and the people pay 50k a year in tuition want to have a brand name degree so that just ended up working itself out.
 If we instituted this scheme in our public schools, we could come up with a pricing structure for a desired GPAs that still undercuts the private schools.
 It would sort of be an unofficial tax on the families of the more wealthy students. With any luck, this will provide some much-needed relief to schools across the country. Now some people may criticize this plan by saying this gives kids who come from money an unfair advantage, but isn't that the case anyway?