Except as provided in § 12-609 of this subtitle as to a motor vehicle, and notwithstanding the provisions of any other statutory law, in the retail sale of consumer goods bought under an installment sale agreement, including any add-on contract described in § 12-618 of this subtitle, the finance charge may not exceed the greater of: An amount computed using the following annual simple interest rates of finance charge: 22 percent on that part of the outstanding balance not exceeding $1,000; and 18 percent on that part of the outstanding balance exceeding $1,000; or A minimum charge of $10 or, if the date of the last installment is eight months or less after the effective date of the installment sale agreement, $8. Notwithstanding the provisions of subsection (1) of this section, a seller may charge a finance charge at a rate not in excess of 24 percent per annum simple interest on the outstanding balance under an installment sale agreement made on or after July 1, 1982.