wiper control arms

Hi, my 1986 Camry has needed these 18" metal bars (which coordinate and control the wipers themselves) to be replaced several times. It's never the metal bar that is worn or damaged but the small plastic "knuckle" at either end of the bar that breaks. I know that these parts are unchanged for the years 1983-86. I currently need the left one which controls the driver side wiper. Anyone able to help? Best quote I can get from Toyota is far too high for such a simple part. Cheers