Ariz. Rev. Stat. § 45-1707
A. The authority:
C. Any resolution or resolutions or trust indenture or indentures authorizing or securing any bonds or notes or any issue thereof may contain provisions, which shall be a part of the contract with the holders thereof, as to:
D. It is the intention in the enactment of this article:
F. The authority shall have power out of any funds available therefor to purchase bonds or notes, which shall thereupon be cancelled, at a price not exceeding either of the following: