For the purpose of determining the amount of payments to States for carrying out part B (or to an Indian tribe under part C), the non-Federal share, subject to such limitations and conditions as may be prescribed in regulations by the Commissioner, shall include contributions of funds made by any private agency, organization, or individual to a State or local agency to assist in meeting the costs of establishment of a community rehabilitation program or construction, under special circumstances, of a facility for such a program, which would be regarded as State or local funds except for the condition, imposed by the contributor, limiting use of such funds to establishment of such a program or construction of such a facility.