I don't remember it being $50. Mine still works.
Looked it up. Not $50: Valve Washer - Toyota (85321-60050) | Toyota Parts
Plug and play
Looked it up. Not $50: Valve Washer - Toyota (85321-60050) | Toyota Parts
Plug and play

like this?
I use distilled water and have had to replace my OEM diverter every 2-3 years. I think the last one I bought lasted just over a year.