That's fair. But then why ask the student to pay, rather than the employer?
As far as recruiting fees go, when employers make a decision on salaries, they look at the total employee cost. If the employer needs to pay a recruiting fee, that goes into the cost. There ain't no such thing as a free lunch, etc, etc. :-)
It would be even lower risk for the student if the hiring company paid, which is a standard practice -- referral fees as a percentage of the referral's first-year salary.
15%-20% is the standard.