Prep books for the standardized tests might be a good investment.
Kids with good grades who score decently on the ACT and SAT can get $1500 to $3000 per year at NDSU. Kids would have to take their math classes to have a shot at the SAT scores needed.
Update: Looks like NDSU has been seeing a lot of activity on that front because they've bumped up the SAT scores to get the $3000 per year from 1400 to 1450.