Ah, but this problem already exists in the present system! If compulsory education were abolished, the price of education would fall considerably, for the artificial increase in demand would cease to exist. Also, if the public schools were made private institutions, there would be more competition in the education field, increasing the quality and decreasing the price further still. Theoretically, the price of education should approach zero in a free market, for knowledge can be duplicated indefinitely and therefore is not a scarce resource.
Equal opportunity cannot be achieved through the decrees of the State. Public education is criminal, and as such it must be abolished. The real route to equal opportunity is to abolish the priviliges for the rich that the State currently upholRAB - the credit monopoly, the patent monopoly, corporate welfare, moralism, and the exclusive ownership of spatial locations (a.k.a. "real property.") Most people do not realize it, but the Free Market is actually a very egalitarian system.