In the meantime, I am working on my 1954 Superior, for non-Ghostbuster purposes. I wanted a Propelloray, but for this car it doesn't have to be screen accurate.
For under $100 I reworked two very accessible items, and combined them into an "Artificial Propelloray" Basically I took the guts out of an Amber Warning Beacon and put them into a Baja Roll Bar Light Bucket.
The results are pretty darn close.
Here is a link to the video https://youtu.be/YDBpUmJoPbg
And here are the links to the photos of the build (I tried to embed them but it's not doing what I want it to)