I'm really fond of Holberton's tuition scheme, where you pay 25% of your salary for two years after graduation. In this scheme, everyone is incentivized to help the student get a high paying job, so the school simply can't become a degree factory.
But Udacity's part-time remote program is $299 a month, https://www.udacity.com/nanodegrees/nd009 so charging by percentages is less worthwhile.