(a) The operation, maintenance, and improvement of historic sites described by Subchapter C shall be financed from the general revenue fund, the historic site account, other accounts that may be authorized by law, and donations, grants, and gifts received by the commission for these purposes.
(b) A donation, grant, or gift accruing to the state or received by the commission for the purpose of operating, maintaining, improving, or developing historic sites described by Subchapter C may not be used for any purpose other than the operation, maintenance, or developing of historic sites.