All bonds shall be sold at public sale upon sealed proposals, except that bonds may be sold at private sale:
Any purchaser of bonds at private sale, other than a public body, shall deposit a certified or cashier's or treasurer's check drawn upon a bank or trust company in an amount equal to 5% of the amount of bonds purchased and such amount shall be applied as in the case of a deposit made at a public sale.
Any private sale of bonds shall be made or confirmed by resolution of the authority adopted by not less than a 2/3 vote of the full membership thereof, setting forth the date, maturities, interest rate and price of the bonds and the name of the purchaser.
N.J.S. § 40:37B-20