Where the cost of services is to be recovered on other than a fee basis, upon receipt of a request from a State or local government for such services, a written reply shall be prepared by the service or staff office receiving the request stating the basis for reimbursement for the services to be performed. The proposal shall be based on an estimate of all direct costs, such as salaries of personnel involved plus personnel benefits, travel, and other related expenses and on such indirect costs as management, supervisory, and staff support expenses. An appropriate surcharge may be developed to recover these indirect costs. The terms thereof shall be concurred in by the Director of Administration. Acceptance in writing by the requester shall constitute a binding agreement between GSA and the requesting governmental unit.