That is an outstanding question dmartin.
But sadly in order for this situation to NOT be an "improper benefit" the chick in question would not only have to sleep with the entire K-State campus, but she and the store would have to offer the exact same "discounts" to the entire campus as well. (well, mainly just the part about the "discounts")
By NCAA rule, any benefit that is given to a student athlete is considered an improper benefit if it is provided by a person/entity representing K-State's athletic interests only to a student athlete. For it not to be considered an improper benefit the same thing would have to be provided to all K-State students.