Subject to the rights of holders of bonds, the Authority shall have the power out of any funds available therefor, to purchase bonds of the Authority, which shall thereupon be cancelled, at a price not exceeding:
(1) If the bonds are then subject to optional redemption, the optional redemption price then applicable plus accrued interest to the next interest payment date thereon; or
(2) If the bonds are not then subject to optional redemption, the optional redemption price applicable on the first date after such purchase upon which the notes or bonds become subject to optional redemption plus accrued interest to such date.