Here is listing on Ebay for GR valve cap that wants $69.50....still way too high IMO....
TOYOTA 86 GR Tire Air Valve Cap 4pcs GAZOO RACING Genuine Parts OEM JDM 08457
sorry to hear...it surely fixed my issue I had with the plunger rattling....while you had the door panel off did you inspect some other surrounding areas?
A few more pics and link to website
Artisan Spirits
â– REAR WING ÂĄ 120,000 ($1135.63 USD) G 4W-8W FRP
â– CARBON REAR WING ÂĄ 198,000 ( $1873.78 USD)GT 4W-8W CFRP