No person may plead the defense of usury or maintain any action thereon or therefor for the interest charged on the unpaid balance of a contract for the sale and purchase of personal property which was not purchased primarily for personal, family or household use or real property if the purchase was made after May 1, 1980 and prior to March 1, 1981.

Severability—1981 c 78: See note following RCW 19.52.020.