The authority, subject to such agreement with noteholders or bondholders as may then exist, shall have the power, out of any funds available therefor, to purchase notes or bonds of the authority, which shall thereupon be cancelled, at a price not exceeding:
(1) If the notes or bonds are then redeemable, the redemption price then applicable plus accrued interest to the next interest payment thereon; or
(2) If the notes or bonds are not then redeemable, the redemption price applicable on the first date after such purchase upon which the notes or bonds become subject to redemption plus accrued interest to such date.