The authority, subject to such agreements with noteholders or bondholders as may then exist, shall have power, out of any funds available therefor, to purchase bonds, including refunding bonds, or notes of the authority.

If the bonds or notes are then redeemable, the price of such purchase shall not exceed the redemption price then applicable plus accrued interest to the next interest payment date thereon. If the bonds or notes are not then redeemable, the price of such purchase shall not exceed the redemption price applicable on the first date after such purchase upon which the bonds or notes become subject to redemption plus accrued interest to such date. Upon such purchase, such bonds or notes shall be canceled.