Any contract for electronic data-processing goods and services, to be manufactured or performed by the contractor especially for the district and not suitable for sale to others in the ordinary course of the contractor’s business, may provide for such terms and conditions as the district deems necessary to protect its interests including, but not limited to, progress payments as the work is performed, provided that at least 10 percent of the contract price is required to be withheld until final delivery and acceptance of the goods or services, and that the contractor is required to submit a performance bond of at least one-half the total payable under the contract.