From the mailer and email from the school:
"For the first time in history, the University of Oklahoma ranks first in the nation among both public and private universities in the enrollment of freshman National Merit Scholars!
We hope you decide to join our over 750 National Merit Scholars already enrolled at OU. The Sooner family won’t be complete without you, xxxxx!"
That’s the total number on campus, not the number enrolling.
Here’s a link explaining the cost:
http://www.ou.edu/go2/connect/nationalmerit/nmparents.html
I’ll have to say they do an excellent job with their recruitment efforts.