An applicant or recipient shall be permitted to retain, without effect on his eligibility for aid or the amount of aid to which he is otherwise entitled, the tools of his trade necessary to continue or seek employment and an automobile of reasonable value needed to seek or maintain employment in order to enable the applicant or recipient to become self-supporting. The board of supervisors shall determine what tools of the trade may be retained as necessary and the reasonable value of an automobile used to seek or maintain employment.