The rate at which the board of directors shall calculate the sums to be charged under Section 185-30 is the average per capita operating cost for all persons receiving the benefit of the facilities or services computed for each fiscal year. The board may, however, in its discretion, set the rate at a lesser amount than the average per capita cost. Lesser amounts may be accepted by the board when conditions warrant that action or when money is offered by persons not liable under Section 185-30. Any money received under this Section shall be paid into the township Fund for Persons with a Developmental Disability.