Warrants issued hereunder may be sold at such price or prices as the issuing board of education may deem advisable; provided, that no series of warrants issued hereunder shall be sold at a price resulting in an average annual net interest cost to the issuing board greater than eight percent computed from the date of the warrants to their respective maturities and taking into account any premium or discount reflected in the sale price.
Ala. Code § 16-13-97 (1975)