Any contract entered into and approved in the manner provided pursuant to Section 41913 may entitle the approved driver training school to payment by the school district of the sum of not more than 150 percent of the amount reimbursable to the school district as “excess cost” provided pursuant to Sections 41306, 41900, and 41903. In the event that a student who has commenced the driver training for which the district has contracted pursuant to Section 41913 and the student does not complete the driver training for any reason, the approved private driver training school may be paid a portion of the contract price which is proportionate to the amount in “excess cost,” if any, received by the school district for such student, compared to the amount the district would have received had the student completed the training.