Dear mid-60s Buick parts hounds,
I'm not sure what is causing the NOS parts to turn up on eBay but there is now a Buick NOS 1965-66 Flasher Hazard Warning Lamp Kit for sale:
https://www.ebay.com/itm/145392014587The seller is certainly asking for a lot of coin for this item.
We shall see!
Edouard