(a) Except as otherwise provided in this chapter, the Authority may invest funds in:
(1) Direct obligations of the United States;
(2) Obligations as to which the timely payment of principal and interest is fully guaranteed by the United States;
(3) Obligations of the federal intermediate credit banks, federal banks for cooperatives, federal land banks, federal home loan banks, federal national mortgage association and the government national mortgage association;
(4) Certificates of deposit or time deposits constituting direct obligations of any bank as defined by the laws of this State. However, investments may be made only in those certificates of deposit or time deposits in banks which are insured by the Federal Deposit Insurance Corporation or its successor if then in existence; and
(5) Withdrawable capital accounts or deposits of state or federal chartered savings and loan associations which are insured by the Federal Savings and Loan Insurance Corporation.
(b) Securities may be purchased at such time and at such prices as the Authority determines.