Abolishing tertiary fees would cost $568 million, they reckon, and making student allowances universal $570 million.
That is a pretty material increase on what the taxpayer already spends on tertiary education, which is north of $2 billion a year.
Wisely, they have not attempted to quantify the cost of "ending the iniquity of student debt".
Internet Mana's policy on that includes no interest on existing loans, increasing the income threshold at which repayments begin and developing a comprehensive loan forgiveness programme starting in 2016 for those with existing debt.
It is worth remembering, first of all, that student loans and the other elements of user-pays-some were the trade-off for a very large widening of access to tertiary education.
Secondly, student borrowers benefit substantially from having the full faith and credit of the New Zealand Government interposed between them and the savers who ultimately finance their loans.
When the Government borrows money the interest meter starts running from day one.
It has to repay the principal at a date certain.
And it always repays it in full.
None of those three things is true of student debt.
The mathematical consequence is that there is a wide gap between the nominal value of the student loan book ($14.2 billion as of last June) and its fair value ($8.7 billion).
The nominal value is essentially the amount lent out which is still outstanding plus accrued interest yet to be paid.
The fair value is an estimate of what an informed and rational purchaser would pay for this asset, in light of such things as how long it takes people to pay off their student loans, the time value of money and the proportion that gets written off.
The difference, currently 39c in the dollar, is an indication of the subsidy implicit in the scheme. So let's set aside for the moment the fiscal cost and moral hazard of wiping existing student debt.
And let's pretend that there is $1.1 billion of new money available to fund abolishing fees and making student allowances universal.
Would it be the best use of that money?
A report from the OECD last week on the link between numeracy and socio-economic status suggests there might be a more pressing claim on those resources. At least the Mana side of this electoral alliance should think so.
Every three years the Programme for International Student Assessment (PISA) measures 15-year-olds' mathematical proficiency.
In the latest (2012) survey New Zealand ranked just above the OECD average.
The problem is that our score has been deteriorating since 2003 when the first PISA maths survey was undertaken. In fact of the 64 countries covered, only three have deteriorated more than New Zealand has.
Compared with 2003 the proportion of Kiwi kids in the top proficiency band has declined by 5.7 percentage points and the proportion in the lowest band has increased by 7.6 percentage points, to 23 per cent. The latter "risk facing difficulties using mathematical concepts throughout their lives", the OECD says.
It is not just performance that has deteriorated. Equity has as well. That is, the extent to which students' socio-economic background predicts how well they will do at maths has increased in New Zealand's case, bucking the international trend.
PISA measures students' socio-economic backgrounds from information they provide about their parents' education and occupations and by how many books there are in the home and whether there is a desk to use for studying - that sort of thing.
When they plot how strong the relationship is between socioeconomic status and performance, New Zealand is well and truly on the wrong (high) side of average, alongside Costa Rica. We rank worse by this measure of equity in education not only than most European countries but also the United States, which we like to think of as a much more unequal society.
And as with performance, the trend is not our friend. In only four countries has equity deteriorated more than here.
All of this highlights one of the ways the country pays a price for income inequality.
It is all well and good that high-level indicators of income inequality like the Gini co-efficient have been going sideways since the massive deterioration which occurred between the mid-1980s and the mid-1990s.
When we look at more granular indicators, like household income after housing costs, or this PISA-based measure of equality of opportunity in the education system, a more troubling picture emerges.
So if there were another $1 billion a year available to spend on education, increasing the subsidy to tertiary students does not look like best bang for buck.
Internet Mana argues, of course, that "we do not have to trade off free tertiary education against other important things".
It offers some suggestions about how it could be funded.
One would be to forget the tax cuts the National Party has (conditionally) promised for 2017 or that Labour has suggested might be on the cards in its second term.
But by 2017 there will have been seven years of fiscal drag since the income tax rates and thresholds were last adjusted. So while it suits politicians to describe them as tax cuts we are really only talking about correction for tax bracket creep.
Alternatively, Internet Mana suggests abolishing tertiary fees and the targeting of student allowances would be a better use of the proceeds of the Greens' carbon tax or Labour's capital gains tax than those parties have in mind.
That would make for interesting Government- forming negotiations: "So have I got this right? We get the odium of introducing a new tax, while you get the credit for spending the money? "
Or how about introducing a new 40 per cent tax bracket on incomes above $110,000?
Internet Mana estimates that would raise $750 million a year.
Census data suggest that would affect about 150,000 people.
Whether it would affect the students themselves in later life (as Internet Mana assume) is a moot point, however.
The risk is that the prospect of a more progressive tax system simply becomes another reason for many of them to take themselves off to join the Kiwi diaspora.
