Yes I worked it out. Assuming the lowest possible cost of services - and excluding welfare (this is assuming employment is found), at an average life expectancy of 78 - an 18 year old who could have gotten a degree but can't afford one will, earning untaxed minimum wage, over the next 50 years of life cost the taxpayer at least 5 million rand. That's without considering inflation - which has the effect of multiplying that severely.
A standard 3 year degree costs about half a million in total (that's with a housing and pocket money allowance).

So what would you RATHER be paying  ? A R5-million rand subsidy or a half a million rand subsidy ? Even if there were no profit from the investment (and, again, the international average return on investment for free higher education is 700% profit - no other investment can come close, government or private) that alone would justify it. 

Make university free - and we can all pay a LOT less tax.