(a) Any builder or sponsor proposing to construct one or more dwellings in an area designated as eligible for direct loans may apply for a commitment for the reservation of direct loan funds to be used for the making of loans to eligible veterans for the purchase or construction of such dwellings. Such commitment may be issued on such conditions as the Department of Veterans Affairs determines to be proper in the particular case and will be valid for a period of 3 months; Provided, That the Department of Veterans Affairs may, for good and sufficient reasons, extend the period of the commitment. No commitment shall be issued unless the builder or sponsor shall have paid an amount equivalent to 2 percent of the funds being reserved, which amount shall be nonrefundable. The commitment shall be nontransferable except with the written approval of the Department of Veterans Affairs.